timed out while sending message body

[randall <randall@songshu.org>]

hi all,

today i started receiving complaints that with some mails the attachment 
was not received or the mails not received at all.

this seems to be happening so far only with 2 receiving mail servers in 
China, these 2 have been receiving mail from my side for years already 
without any problems and the messages below only started appearing today

i use a zimbra setup (which uses postfix) and did no changes to the 
setup at least for the last month, i restarted the server today just in 
case but this had no result.

Aug 20 14:02:26 mailro postfix/smtp[12590]: 3A2F5352D4CE: 
to=<jane@example.com>, relay=mail.example.com[221.4.158.196]:25, 
delay=3140, delays=2403/0.01/3.9/733, dsn=4.4.2, status=deferred 
(conversation with mail.example.com[221.4.158.196] timed out while 
sending message body)

anybody has a clue or similar experience?


Greetings,

Randall