Aquamail broke for me yesterday on 2 phones that are using Outlook accounts. Both are running version 1.42.0-255. This brings back memories of the ongoing Outlook account problem from not so long ago where the app wouldn't receive push email.
Email won't send. The error I'm seeing when the application fails to send is:
Outgoing server login error: 535 5.7.3 Authentication unsuccessful.
Another phone with the same version of Aquamail linked to a Gmail account is not having any send issues.
Looks like I'm back using the Outlook mail app until this is fixed.