Newsletter Blast sending duplicates to subscribers using mailman

mrddoug

Registered
Jan 8, 2014
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Website Owner
Hi,

We've been using mailman for quite a long time now, and suddenly the last newsletter we sent out sent duplicates to random users as far as I can tell.

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.

I have a few accounts added to the list myself, and my aol account did not recieve the email at all. Previously the aol account received the messages, I had a couple of the newsletters in my account still unread.

So, my question specifically... does anybody have advice in what I should look for as to why this happened? I read a post from 2002 that was somewhat similar to this issue, but it had to do with not haveing enough memory... and currently my server has 53gigs free, so that couldn't be the issue... unless of course you have to 'allocate' memory to mailman in some config file. We have about 12k users on our list.

Thank you in advance, and let me know if I lacked some details to help solve my issue.

Thanks,
Doug
 

cPanelMichael

Administrator
Staff member
Apr 11, 2011
47,913
2,201
363
Hello :)

Could you try searching for one of the email addresses that received duplicate messages in the /var/log/exim_mainlog file? EX:

Code:
exigrep [email protected] /var/log/exim_mainlog
Does it show the message getting sent out multiple times?

Thank you.
 

mrddoug

Registered
Jan 8, 2014
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Website Owner
Confirmed, we only sent it one time.

It appears it has nothing to do with our setup. It looks like Yahoo had something messed up with their system and the way they were handling group e-mails... many people having the exact same issue all around.

Thanks!
 

cPanelPeter

Technical Analyst III
Staff member
Sep 23, 2013
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Root Administrator
Twitter
Hello,

I'm not sure if this is still the case, but Yahoo mail servers used to separate messages that were sent to multiple recipients. In other words you send something to [email protected] and [email protected] and ([email protected] forwards to [email protected]). Many mail servers will detect that it is the same message going to the same person and will only deliver one copy.

But Yahoo would separate all those into their own copy and then deliver the message twice.

It's possible this is still happening with them.