[Mailman-Users] Meaning of "Postfix SMTP server: errors from dd11328.otherdomain.tld[ip.ip.ip.ip]"

[Mark Sapiro]

On 5/9/16 2:04 PM, Kala Balik wrote:
> 
> today we ran our first mailing over our new Mailman instance. We
> received a few bounces and the following email which left me clueless.
> 
> Please, what is this message trying to tell me? Is this us sending out,
> or is this someone trying to answer to our mailing (and failing to log
> in via TLS)? I checked my /var/log/mail logs - to no avail.


This apparently has nothing directly to do with Mailman on your server.


> Transcript of session follows.
> 
>  Out: 220 lists.domain.tld ESMTP Postfix (Ubuntu)
>  In:  EHLO dd11328.otherdomain.tld
>  Out: 250-lists.domain.tld
>  Out: 250-PIPELINING
>  Out: 250-SIZE 10240000
>  Out: 250-VRFY
>  Out: 250-ETRN
>  Out: 250-STARTTLS
>  Out: 250-ENHANCEDSTATUSCODES
>  Out: 250-8BITMIME
>  Out: 250 DSN
>  In:  STARTTLS
>  Out: 454 4.7.0 TLS not available due to local problem
>  In:  MAIL FROM:<> SIZE=236
>  Out: 250 2.1.0 Ok
>  In:  RCPT TO:<list-bounces at lists.domain.tld>
>      ORCPT=rfc822;list-bounces at lists.domain.tld
>  Out: 250 2.1.5 Ok
>  In:  RSET
>  Out: 250 2.0.0 Ok
>  In:  QUIT
>  Out: 221 2.0.0 Bye


It looks to me like the server that identifies itself as
dd11328.otherdomain.tld started to send a message (probably a legitimate
bounce of a list message) to <list-bounces at lists.domain.tld>. It send
the RCPT TO:, was sent an OK in reply and then instead of sending the
DATA, reset the connection and quit. Possibly this is because the
sending server requires TLS which your Postfix says is not available.

Why your Postfix decided to notify you of this is a Postfix question.

I suggest you set both

smtp_tls_security_level = may

and

smtpd_tls_security_level = may

in your Postfix main.cf so that you accept incoming TLS if offered and
offer outgoing TLS. You will also need to set smtpd_tls_cert_file and
smtpd_tls_key_file and maybe others. See
<http://www.postfix.org/TLS_README.html>.

-- 
Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan