[Mailman-Users] Newsletter Blast sending duplicates to subscribers

Grant Taylor gtaylor at tnetconsulting.net
Thu Jan 9 07:03:31 CET 2014

On 1/8/14, 10:03 AM, Doug Hutson wrote:
> All the people that have e-mailed us about this issue were specifically
> yahoo addresses.  Reports of 4-50 duplicates per user were sent to
> them.  We only have one list of users we send users to, and this is the
> first time this has ever happened.

The few times that I ran in to this type of problem in the past were not 
Mailman issues at all.  Rather they were symptoms of underlying SMTP 
issues.  My clue when I fought this battle before was that the messages 
IDs down stream of my server(s) were different in each ""copy of the 
message.  When investigating in my SMTP logs, I found that the delivery 
attempts were failing in some manner and my SMTP server was considering 
the delivery a failure and would retry until it saw the expected 
response.  However, the receiving server did considered the delivery to 
be successful, and as such treated the message(s) as valid.  Ultimately, 
causing duplicated messages.

When investigating the SMTP issue, I found that the problem was related 
to network connectivity issues, specifically saturated connection on the 
receiving end.  -  Once I addressed (worked around) the connectivity 
issues, the duplicate messages cleared up immediately.

Grant. . . .
unix || die

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