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

[Kala Balik]

Dear List-Members,

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.

Thanks for your answers!

Cordially,
KB


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


For other details, see the local mail logfile