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Re: OT: dovecot with letsencrypt, K9 mail fails?

On 16/03/18 16:15, Anthony DeRobertis wrote:
> Dovecot (IMAP) is working fine here with K-9.
> Since you're seeing different results in different clients, the most
> obvious reason would be a different behavior from the two different ways
> to connect to IMAP (or POP3) with TLS:
>  * connect to port 993, start TLS negotiation
>  * connect to port 143, run STARTTLS command, start TLS negotiation

Both are 143/STARTTLS.

> You can debug both with OpenSSL's s_client:
> openssl s_client -starttls imap -connect MAIL.YOURDOMAIN.COM:imap
> openssl s_client                -connect MAIL.YOURDOMAIN.COM:imaps

Thanks, will have a play with that. Unfortunately, it seems to be
intermittent (and relatively rare). Maybe it's just coincidence that
Thunderbird never sees it ...

> If you're seeing this on sending mail, that's SMTP — and there are
> /three/ SMTP ports you might be using: 25, 465, and 587. 25 and 587 need
> STARTTLS. s_client can deal with those, too.

Haven't seen it with SMTP, but then I don't often send from K9. Typing
is so much easier on a proper computer :-)

> Once you've figured out what's happening, then you can determine if it's
> something weird on your server or your VPS providers' network.

Thanks :-)


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