WP8/Windows 10 mail app can't login, tries double auth

[Joseph Tam]

Attila Nagy writes:

> Are there anybody who could make WP8 (and W10 desktop clients it seems)
> devices working with Dovecot's POP3 server?
>
> The conversation looks like this:
> S +OK ready
> C CAPA
> S +OK
> S CAPA
> S TOP
> S UIDL
> S RESP-CODES
> S PIPELINING
> S AUTH-RESP-CODE
> S USER
> S SASL PLAIN
> S .
> C AUTH
> S +OK
> S PLAIN
> S .
> C AUTH PLAIN
> S +
> C <base64 auth string)
> S +OK[space]
> C USER username
> S -ERR unimplemented
>
> First I thought the extra space after that OK causes this, but removing
> it changed nothing.
>
> So these devices try to log in with AUTH PLAIN, then even after a
> successful login they want to log in again with USER, which gets rejected.

I dimly remember some Windows clients preferring either "LOGIN" or "PLAIN"
style mechanism.  Have you tried allowing "LOGIN" style authentication?

 	auth_mechanisms = plain login

Joseph Tam <jtam.home at gmail.com>