Andrew Simpson - 2016-11-11

Very interesting. What you've done looks correct and it was working.
Everything works fine until WebCollab asks to authenticate by AUTH PLAIN to which the server replies '334' (O.K. to proceed). Then authentication with user and password fails.

WebCollab then asks to use AUTH LOGIN which is also accepted with '334' and a base64 encoded request for username. Trying alternate forms of authentication is permitted by the RFC. However that fails too.

After that there are no other forms of authentication available and WebCollab has to abort.

I have double checked the relevant RFC's and WebCollab is correctly following the protocol for AUTH PLAIN and AUTH LOGIN. I guess your username and password is correct.

Looking around the web, I think that Gmail will 'ban' addresses that fail authentication more than a few times - or even try more than form of authentication in one session. There is an interesting article here:

http://www.webholism.com/blog/sara/gmail-suddenly-stopped-sending-my-business-emails/#

I will try connecting to Gmail myself and see if that works.