The Gmail app 'freezes' when I try to send a tracked email from the Gmail app on my phone

If the Gmail app 'freezes' when you try to send a tracked reply or new tracked email using the Mailtrack mobile add-on then this will normally be because Conversation View is not enabled for the Gmail account concerned (unfortunately, our mobile add-on can only work if Conversation View is enabled).

To enable Conversation View:
 

1. Log into Gmail on your computer.
2. In the top right-hand corner, click Settings.
3. Click Settings from the drop-down menu that appears.
4. Scroll down to the "Conversation View" section.
5. Select Conversation view on.
6. At the bottom of the page, click Save Changes.

Once you've done that, if you switch your phone off then switch it back on again, you should no longer experience issues.