[njhaveri]

This is something I asked about a few years ago when it was first introduced, and the vague answer I got is that the warning exists because the Gmail API is not as optimized as IMAP for some common email client tasks. (Indeed, for better performance, I would like to switch a few tasks to use IMAP instead of the Gmail API someday).

Google did vet Mimestream as a general-purpose email client before approving API access, and on the paperwork for that process "general purpose email client" was the app category that I selected, so I'm hoping all will be OK, or else I will be really scrambling to implement new protocols :P