Fixing Sidekick for Apple Mail on OSX El Capitain and later

Update: the below no longer works (as of ~2018?) given the Sidekick rebrand (to Hubspot Sales) and Apple Mail’s plugin lockdown.

Sidekick is one of the best mail¬†utilities out there.¬†Especially on OSX, combining the power of Apple Mail, and the possibility to track your email opens, it’s one of my favorite apps.

Unfortunately, the Hubspot team dropped support for Sidekick for Apple Mail, starting at OSX El Capitain. That said, the current app only does support OSX 10.11.0; Sidekick will cease to work if you update to OSX 10.11.1 or later (10.12 as of the time of this writing update, on the stable channel.)

The video below explains exactly the steps to take to reactivate Sidekick for Apple Mail. Tested on OSX 10.11.0, 10.11.1, 10.11.2, 10.11.3, 10.11.4 (respectively Apple Mail version 9.0, 9.1, 9.2, 9.3, and 9.4.)

For MacOS 10.12 / Sierra, read the update below.

PS: If you’re into the technical details, below the video is a brief explanation.

The SupportedPluginCompatibilityUUIDs key in the Sidekick Info.plist file, is sort of a manifest for the plugin, declaring itself compatible to Apple Mail client UUIDs (Universally Unique Identifiers.)

What we did was simply get the¬†system’s current Apple Mail’s UUID (from /Applications/, and add it to that list!


Sidekick removed the download section of their¬†Apple Mail’s plugin, but here’s a¬†direct download link:¬†¬†(no longer works);¬†

“Login URL is invalid” error

If you get the “Login URL is invalid” while logging in using your Google account, try to set a password for your account, and login via your email/password (creating a new email/password¬†account is the easiest way to do so.) — Restart Mail after you do this.

Thanks to Jonathan Wizman and Vinny Troia for pointing this out.

Update: OS Sierra

Thanks Spike for the suggestion and Elijah for testing.

On MacOS Sierra, you should ALSO replace the SupportedPluginCompatibilityUUIDs key (inside Info.plist) with Supported10.12PluginCompatibilityUUIDs. And Voilà!


Leave a comment – I’d be more than happy to help.

Join the Conversation


  1. Would you mind helping me? I’m not as tech savvy as you but I love Sidekick and would love to get it working again on my Mac.

        1. hi Zak!
          I just installed Sierra and wasn’t sure exactly how to get my sidekick running based on what you wrote above.
          Do you have step-by-step list for us non-techies?

          Thank you!!!
          Brian, NYC

  2. Zak El Fassi helped me fix Sidekick on my iMac – he was very helpful in getting this working again!

    1. Robert, would you be able to help me too? I’m on Sierra.

  3. Thanks Zak! Definitely adding this to my favs even though 9.2 is currently working with 10.11.2 beta. The official osX is waiting to be updated… very hesitant to download it. Any thoughts?

    1. Hey Scott,
      I’m currently on 10.11.2 stable channel, and everything appears to work just fine!

    2. Totally forgot about this fix. All is working except… the notification that usually pops out, top right of screen is not for any email sent with the new fix.

      Any old notification, either sent through the iphone, gmail, etc still pops.

      any thoughts?

  4. hi Zak
    You are a lifesaver…I am Currently on 10.11.3 and apple mail 9.2. and my friend did what you said in your video and right now I am email tracking on the web based hubspot dashboard, but, I am not seeing the notgifications that fly in on the top right side of the browser.

    Do you still get the flying notifications in your set up and perhaps something might have been done wrong on my end?

    Thank you in advance!

    1. Happy that helped!

      As for the notifications, yes, I still get them – but only sometimes on Chrome. It could be a bug in Sidekick’s extension.
      The notifications work better on mobile IMHO.

      1. Yes I am getting them now…not 100% but close enough..thanks once again..I was actually considering spending a lot of money to install windows on my mac, then purchase Window10 and then purchase outlook for windows….

        If you are ever in NYC I owed you a coffee or 3!

  5. Hi Zak,
    I use OS Yosemite 10.10.5 and Mail Version 8.2., so I think I should be able to use the normal sidekick plugin. But The thing is I can’t find it online anymore?
    Could you maybe send me the “old” sidekick plugin for Apple Mail?
    That would be really great!


    1. Hi Peter,

      Technically, the new version is backwards compatible – and the new version should work. If not, the steps described here would solve the problem! Hit me up if you have any question >> z [~AT~] kelfassi [~DOT~] com


      1. Hi Zak,
        thanks, but the thing is the new version is available online. At least I can’t find it. Do you maybe have the file, and you could provide? I sent you a personal e mail earlier, with my e mail address.

        Appreciate it!

    1. Not sure if they still offer the installer for Mac (also, I’d suggest not trusting any third-party site with an installer!)

  6. Hi guys,
    You should all know, that Zak is amazing, and has just supported me to install Sidekick on Apple Mail (I still use Version 8.2). Thanks Zak, appreciate it very much!!!!
    To everybody who uses this plugin: Are yo guys able to access your templates from Apple Mail? I don’t see any button, where to enter is from?
    It should be able to pull the template from Hubspot, once I define the recipient of the e mail.


  7. Hello,

    Thanks Zak — great info !!!

    So I got it working, except the ‘tracking’ is not working exactly…
    On the sidekick stream, it ONLY is tracking sends… not open, not clicks ?

    I have El Capitan 10.11.3 (so latest mail and sidekick for mac)

    I’m not sure why its not tracking opens/clicks.
    I did a test from gmail — same issue? So that tells me its not a mac/apple issue?

    NOTE: I did see the tracking url was on my test email… really odd its not tracking clicks?


    1. Hi Larry,

      Sidekick attaches the IP address to the tracking “pixel” – so you probably won’t be able to trigger the open/click; try to open from your phone’s mail client (or send me a mail > z [~at~] kelfassi [~dot~] com )

  8. H1 ZAk,

    had mange to get it back on 10.1.4 today with your tip. that said, had the app Sid8¬ß‚Äʬ™king over on my iphone even though my hubspot integration over at my mbp had reached its month limit .

    unfortunately, after the update 10.1.4 and even thought your trick worked, iphone spot showing me who opened the messages.

    any ideas.??

  9. Hi Zak,

    Would you mind helping me? I‚Äôm in anyway a tech connoisseur as you but I love Sidekick and would love to get it working again on my Mac. I’m running El Capitan 10.11.4 and mail 9.3.


    1. Did you try to follow the steps as shown in the video, with no success?

    2. I just got my sidekick working on the exact same version as you…following Zak’s video tutorial….good luck

  10. Tried like your tutorial but when I click on login in the mail app preferences; I only get a white rectangle…
    Any idea on what’s wrong ?
    El Capitan 10.11.3
    Mail app 9.2


    1. Eric, could you try removing the plugin and starting with a fresh install? (download link above.)

      1. Hi Zak,

        Yes I tried but it still doesn’t work.
        Don’t you think this could be a problem with this first line :
        #For Mail 9.1b3096.4 on 10.11.1 build 15B38b
        As my mail version is now 9.3 and ios is 10.11.4

        Thank you
        Great app anyway ;) !

      2. Hi Zak,

        Thank you for your help!

        I use Apple mail. After doing all the changes you told in your video it seem that I have to uninstall and starting with a fresh install.

        But if I try to start uninstaller there’s just a error page:

        This XML file does not appear to have any style information associated with it. The document tree is shown below.

        Access Denied


        How to remove it and starting a fresh install?


  11. Hey Zak,

    Mate…just wanted to thank you for your simple instructions on how to get Sidekick working.

    Sidekick – now Hubspot Sales, has an app on iPhones and iPads…so if you send an email via that app (With your default email logged into), you can even get notifications, even when you send emails from your mobile phone or iPad….

    Just one small issue…but not a deal breaker…the little “bell” notification on the top status bar on the Mac…just doesn’t show up, when somebody has opened the email…but I think this “bell” notification disappeared when Hubspot upgraded Sidekick for El Capitan….

    Did you get this to work?
    Many thanks for your wonderful video…I now have Sidekick working…


    1. Glad it worked out, Kris!

      Never seen the bell notification to be honest. Maybe you’re talking about Google Chrome notifications?! (in which case it does only appear if Chrome is launched.)

      1. Hi Zak… bad…yes, I did mean the Google Chrome Notifications….but now I don’t bother keeping Chrome open…

        Awesome work there Zak..and thanks again.

  12. Hey Zak,

    Tried like your tutorial but when I click on login in the mail app preferences;
    I only get a white rectangle…
    Any idea on what’s wrong ?
    I’m now El Capitan 10.11.4
    Mail app 9.3


  13. Hi!

    I cannot fint the latest sidekick pkg file since the link doesn’t work above.
    Is it possible that one of you guys have the pkg file on you’re computer and if, can someone e-mail me that pkg file? :)

    Best reegards
    Eddie Johansen

  14. Hi Zak. I have OS 10.11.4. I watched your video but don’t fully understand how to do all of the things you did. Could you help me figure out what to do? Thank you!

    1. Hey Dianne,

      Just sent you an email. We can schedule a quick Skype call to go through this.

  15. Hi Zak,

    I would like to thank you for figuring out how to make SideKick work again.

    Thank you so much!

  16. I tried to login after following the video instructions and I get this error message – “This login URL is invalid.” “Please check that you clicked the correct link, or that you copied the link correctly into your browser.”

    Any thoughts?

  17. Hello,

    Many thanks for taking the time to post this article. I have the same issue when the addin is launched and I try logging in with my google account I get the error “This login URL is invalid.”

    Do you know where or how I can correct this?


      1. Hubspot recently changed Sidekick to Hubspot Sales with 10X increase in price. It might stoppped supported the Mail add-on. Just a guess.

        1. Although it changed, the Mail plugin still works (as it uses the same infrastructure/APIs.)
          Could be a random bug …

  18. Mac Mail 9 .3
    OS X 10.11.4
    Sidekick 2.6.1

    This method is working, the only thing is that the option to “auto track emails” is not available anymore. There is no visual that it is working, but after testing a few messages, it is absolutely working now.

    Thank you so much Zak!!!!

    1. You gotta manually enable tracking it from Preferences>Sidekick panel; (for future ref, in case it doesn’t show, just uninstall the whole thing and run the installer in this post.)

  19. Zach, you rock! Thank you for alleviating a huge headache as I havent had sidekick working since last week via mail. Wasn’t too hard to do and it is back!

  20. Hi Zak!

    I followed your steps but for some reason when I launched Mail, I didn’t have that pop up that says Sidekick has a new version. Really need your help!

    Thank you very much.


  21. Hi Zak, nice video. Done everything, sidekick is on (Mail 9.3), everything looks fine, but actually all messages appear as NOT OPENED in the activity stream. Do you know how to fix this? It actually tracks messages but not when they’re opened.

    1. Hey Andrea,

      You gotta make sure to open the email from another IP address/client to test (eg. nobile phone via 3G); as Sidekick tries to minimize the false positives.

      1. Zak. not sure if you missed this…

        All is working except… the notification that usually pops out, top right of screen is not for any email sent with the new fix.

        Any old notification, either sent through the iphone, gmail, etc still pops.

        any thoughts?

          1. 1/ Sent tracked – Shows in stream as sent and unopened.
            2/Not getting the opens either in the stream or Mac Notifications (or iphone)
            3/ Answered in #2….

            Thoughts? They show as sent, just not as opened.

        1. One thing I can think of (which, only makes sense) is the “tracker” (hidden image sent with the email which fires the open) isn’t being loaded. Maybe images are not being loaded automatically.

  22. Amazing!!! Thank you. It just worked … really can’t thank you enough for this.

      1. Same thing for me… restarted and I am now logged in… Time to test if it works! Thanks so much.

        1. I’m on OS X 10.11.5 Mail 9.3 (3124) Observations:
          1. Crashed my Mail initially but reopened and all good since
          2. Sent mail is being tracked in Activity stream when sent to myself but not tracked when I open in Mail
          3. Opened same email in Outlook for iPhone and it marked it as tracked
          4. Properly added activity records for pipeline as well

          So a little buggy but what a time saver. It’s worth it!

          1. Hey Mike,

            Quick notes:
            1/ It only crashes Mail if the app is still running in the background/not killed (while you’re performing the file edits.)
            2/ That’s how it’s supposed to work, to reduce false flags.
            3/ Your iPhone is recognized as a different device. Hence the opened state.

  23. Thank you for your instructions! I followed them, and I got Sidekick to work again. However, I do not see the box on the actual e-mail window to indicate that I want that particular message tracked. Have you noticed that? I did not see it in your video either. Do you know what might be the cause of that?

    O. Lopez

    1. Glad that helped. The checkbox was removed in later versions due to incompatibilities. You can still enable/disable tracking via the sidekick panel in the Preferences menu.

  24. Like a couple other people I am receiving an error that states :
    “This login URL is invalid.
    Please check that you clicked the correct link, or that you copied the link correctly into your browser.”
    I would gladly send you attach a screenshot but it does not allow me… How can I go about fixing this issue?

  25. Updating the plist dos not seem sufficient to upgrade for Mail 10 (macOs Sierra ) do you have another recommendation ? :)

    1. Haven’t tested on Sierra to be honest – but very likely it will break (as Apple Mail is getting slowly rid of all third-party plugins…)

      Can you check what version of Apple Mail it is?

      1. Hi ZAk,

        all good here on 10.11.6 mail 9.3 (3124). Thinking of updating to Sierra. do pls let me know if you can fix that, i would be nice.

        Warmest regards from S√£o Paulo – Brasil

        1. No idea if this will work on Sierra – will try to upgrade during the weekend and email you with the result :)


  26. HI Zak, I just followed your video and I would like to know why sidekick stream showed that I didn’t open the email ( I sent one to myself )..

    el Capitan 10.11.4
    Mail 9.3

    Thanks Mario

    1. Hey Mario,

      Try opening it from your mobile phone – from another IP address (try 4G/WIFI). Sidekick is pretty smart about avoiding false opens!

    1. Hey Afonso,

      Unfortunately Sierra is still on early beta – couldn’t get on the beta channel for my main dev machine :/

      1. look forwards in hearing from you here when you have a chance to have a look. best

  27. If anyone is having the “login URL is invalid” error, you can NOT log in using Google. You have to set your password and log in manually. Then you will at least get it, close the browser that it opens and quit mail. When you open mail again, it will be logged in.

    1. Hi Amir,

      I haven’t tested this on Sierra yet (as it’s not on the Stable channel, yet). My guess is, if the fix doesn’t work on Sierra, there’s only little we can do about it.

      1. Hi Zak,

        Thank you very much for all of your effort in getting sidekick to work. I’ve used your tutorial many times in the past due to apple OS upgrades. I’m now running Sierra 10.12.1. I got to my mail library via the terminal mode, however when I try opening Sidekick.mailbundle, I get a message stating “Unable to read the dictionary of the application or extension because it is not scriptable.”
        /Users/georgekovo/Desktop/Screen Shot 2016-10-25 at 10.22.47 AM.png
        Any thoughts on what I’m doing wrong?

        Thank you…

  28. Hey Zak,

    Thanks for the detailed explantation – however I’m getting stuck on the “Login URL Is Invalid step”

    I’m using a company Gmail account so I can’t just ‘create a new email account’



    1. Hey Luke,
      You can still create a new account (login/email) and track your Google accounts from within Apple Mail.
      (eg. having a [email protected] login would also track all your Apple Mail emails. The only difference is you’d need to log in using [email protected] in Hubspot Sales.)

  29. Just in case anyone wants to fix this on MacOs Sierra. Adding the following under the array in the info.plist worked for me:



  30. For Sierra, it did work as Spike suggested.

    In a nutshell:

    In the bundle folder, edit info.plist



    1. Hi Elijah.

      Thanks for clarifying this. I followed your steps and I can confirm that everything is working as per normal. Also thanks Zakel for the blog post!

  31. Sierra Works! Thanks Spike!!

    FYI you will have replace the key again in sidekick with the UUID from the new mail plist.



    1. Sierra instructions are simple:

      1. Add your ########### as per the video to the other text file
      2. Add “10.12” in the right spot in this: SupportedPluginCompatibilityUUIDs

      Works fine. Unlike 10.10 where you had a nice check box in a new message, you have to go to Mail > preferences > Sidekick to manually turn of tracking on new messages before clicking “new message”

      Thanks again EVERYONE!!!!!

  32. I confused here. Please guide me on the Sierra workings –

    Do I replace –

    SupportedPluginCompatibilityUUIDs to Supported10.12PluginCompatibilityUUIDs




    After the

    Thanks for your clarification.


  33. Hello, could you please clarify the process to make the sidekick plug-in work with Apple Mail v10

    1. This login URL is invalid.

      Please check that you clicked the correct link, or that you copied the link correctly into your browser.

      1. OK, I was logging in with a Google account which was causing that issue. Did a password reset so that I can log in with just my email and password and no longer get the error, but also the plugin in Mail does not activate with my account details..


  34. hi, i recently updated to sierra and can’t get it working. just did all the things like in the video. using el Capitan this worked. i deleted the old files and then installed the latest package again. now mail shows me the deactivate message. i closed the app and edited the uuids. also added and replaced (tried both) the Supported10.12PluginCompatibilityUUIDs. rebooted but nothing is shown in the setting after starting mail…

    what can i do?


  35. Thank you so much! I rely on Sidekick and I can’t find an alternative that functions in a similar way. I just updated to Sierra and your hack works perfectly.

  36. Hi, Help please I jus updated to Sierra, I followed all the steps, and I cant make it work. If i don’t change the “Supported10.12PluginCompatibilityUUIDs” i get this message: “Contact the makers of these plug-ins for versions that are compatible with Mail 10.0.” And if I change it then my mail doesn’t open.

  37. Hi Zak,

    Thanks for your post! I’ve could fix Sidekick following your tips when I had Yosemite but now that I updated to Sierra, it does not work :(

    I followed all the steps but the notifications don;t work. Any ideas?

    Thanks for your work!!

  38. I am having issues with this fix for Sierra as well. I tried what was suggested here and went further to change the code further. My info.plist is:



    Copyright © 2014 HubSpot. All rights reserved.



    I matched to other bundles to ensure these keys matched from SideKick to other bundles and this didn’t work either — what am I missing?


  39. Hi Zak, thanks for your instructions, but they don’t work for me. The only difference here is that I bought a new Macbook Pro with Sierra and tried to follow your instructions on that. But I still get that incompatibility plug-in error when I open Mail. Please advise.

  40. Hello,

    I am able to install sidekick onto 10.12. However, I can’t sign into the app via Mail > Preferences > Sidekick. Every time I do, it doesn’t save.

  41. I updated to Sierra and followed all the Sierra instructions to get Sidekick to work but now I get this error: “This page requires javascript to work.
    HubSpot apps use javascript to provide a rich and dynamic experience. Please enable javascript in your browser settings to continue using HubSpot. ”

    Javascript is enabled in all my browsers and updated on my system. Can you help?

  42. Guessing there is no sidekick fix for Sierra users? Can you update this page so we know where you are on this please. Happy to pay for a fix if necessary.

  43. Latest update has broken sidekick again

    For mail version 10.3 (3272)

    Add the following mail UUID to the info.plist in the the Sidekick.mailbundle


    Now you have working Sidekick again :-)

  44. Zach and All, I tried to do the usual in editing the Info.Plist for Side Kick. Attempted deleting sidekick and the disabled bundle, rebooting, keeping mail closed, etc but Mail opens during install routine and immediate disables the App before I am able to edit. Mail 10.3 version. Attempted to keep the actual update from ever running but it took over and ran a couple nights ago.


  45. I tried it with Mail on High Sierra (11) and although it starts if you change Supported10.12PluginCompatibilityUUIDs to Supported10.13PluginCompatibilityUUIDs it does require me to login, and I can’t make it accept my login. Anyone was able to figure out how to fix the login issue?

      1. Same issue here. Go through the login, get the login window, I’m logged in but Mail stills not get it.

        Did a few test and send some emails but it doesn’t work.

    1. I’m about to try to change the plugin. However, my guess is HS is asking us to pay for Sales pro now. The login may be the entrance fee. Not sure.

  46. Hi all!

    Sidekick is working for me. All I did was switch out 10.12 for 13. I logged in and it’s all set. Just an FYI, once you are logged in, the sidekick tab will still say login, not log out. It still worked.

      1. Confirmed – I did as Scott says above, and good to go! Thank GOD for this :)

        1. How could you guys Log in ?
          I keep going to the sidekick tab, but I can’t close Mail without this tab reopening..

          Any ideas?

  47. Maybe I am missing something here!!!

    I am not able to login into Sidekick through Apple Mail. And it is not working for me.

  48. Changing it to 10.13 doesn’t work for me either. It does not give the plugin error when I open Apple Mail. After that, before logging into Sidekick, I tried sending an email to myself and I can see a notification on the Hubspot website in my account (under Sales Tools>Notifications). The notification states “Unopened”, even after I open my received email. I then try to login to sidekick from Apple Mail. The Username and password both change from ‘Label’ to ‘Unknown’. After that, I test by sending an email to myself, and don’t even see an Unopened notification. One thing though, when I login to Sidekick from Apple Mail, it opens a window stating “1. Install your tracking code. For HubSpot to work, you need to install the tracking code on your website.” This doesn’t;t make sense to me,
    Any help would be appreciated.

  49. Hi,

    I’ve got a new computer with High Sierra on it, I’ve installed HubSpot and followed the install instructions here, which all appeared to go fine. The issues are as follows: In mail preferences, I see the Sidekick tab, however, the “Username” states: “Label”, the “Account Status” states: “Label,” the overal status states: “Log in”, kind of indicating I am not logged in.

    When I send an email from within Apple Mail, everything seems fine. However, when I open the email from within Apple Mail, (my other email account), it shows as UNOPENED on the HubSpot website under Notifications. When I open the same email by going to and using a web browser (Chrome), it then shows the email has been opened.

    I too switched out 10.12 for 13.

    Does anyone know what’s going on here?

    I have noticed that HubSpot, in general, is very inconsistent, sometimes it states the location and the device it was opened at and by, and sometimes not. Has anyone experienced this and does anyone know of a remedy?

  50. Hi Zak,

    Yesterday afternoon, I started getting the login popup whenever i opened apple mail. did not upgrade anything – OS related or otherwise. When I provide the sidekick/hubspot login credentials, while it accepts, I don’t see they reflecting in the preferences window and Username and Account Status shows “Label”. Any suggestions on how to get this working again? Not sure what caused this since everything was working fine until yesterady afternoon. I am on OSX 10.13.4.

    Thanks for your help!

    1. I’m in a similar position – I’m getting the ‘Login’ window with the ‘Unknown’ fields, although I’ve never upgraded past Mac OS 10.9. I’m wondering if they’re gradually shutting down the API that the Apple Mail plugin used, although it strikes me as odd that it would have kept working for different amounts of time for different people.

      1. Hi,
        I have exactly the same problem. as soon as I open mail, hubspot login window opens, I enter the username and password, it connects to a page but mail does not take anything into account. The tracking does not work anymore, I then connected to my second mac and the same appeared. Do you have a solution ? thank you

  51. I spoke with hubspot support and he confirmed they deprecating the API for apple mail clients, and this change was instrumented two weeks back. I requested that if they can support it and pointed out to this blog page. He cited that there were not that many apple mail clients and hence the decision.

  52. Darn, looks like this is the end of the line for Apple Mail users! We noticed all our MAC’s stopped working with Sidekick about 2 weeks ago, all on the same day a strange blank pop-up started appearing when we open our Apple Mail app. After a while it loads the hubspot login page and appears to login but if you check apple mails preferences (where there is a Sidekick tab if you have the plugin successfully installed), the login does not seem to have worked and no emails from Apple Mail are tracking.

    Such a shame as we have really come to rely on this tool and have to date, not found a suitable alternative. It’ll be a cold day in hell before we all switch to using Microsoft PC’s so hopefully there is a workaround for this new bump, or someone will come up with an Apple friendly alternative.

    Zak, what is your take on this new issue?

  53. I was using a free version of Hubspot over 5 years ago solely for the purpose of getting a notification when an email recipient opened an email I sent them. I was using, and still am using, Mail on a Apple Macbook Pro.

    Every time I open Mail on my laptop a window appears to log into Hubspot. I have no need for Hubspot anymore so I have no need to log in. I have no idea which of 4 email addresses I used to sign up with Hubspot. I’m tired of this window loading when I have no use for it. Do you know how I can disable the window from appearing?


  54. I agree and share your disappointment that Sidekick is no longer supported for Apple Mail. The blame should go to Sidekick. The reasoning on their site, “

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