4.6.2-p23 and [tcp bad cksum]

[Will Froning]

After upgrading my 2 Sendmail servers to 4.6.2-p23 last week I ran into
an amazing issue sending mail to hotmail.com and msn.com addresses.

I noticed it because of the large queue for those domains building up
daily.  In the process of troubleshooting I noticed massive [bad tcp
cksum] messages in the tcpdump of a hotmail queue run.

At first I thought it was a networking problem maybe on our side, maybe
theirs.  To save disk space I moved it to a 4.9-PRE box and ran the
queue for the heck of it.  Amazingly all messages went through.  I was
still experiencing [bad tcp cksum] messages, but at a much lower rate
(enough to process all the messages).

For the heck of it I upgraded the lower volume box to 4.8 (was on my
schedule for this weekend anyhow) and messages started being sent out to
hotmail.com and msn.com address.  Once that worked I upgraded the other
4.6.2 box and mail is going smoothly.

So, this problem didn't happen until -p23 (arp patch).  If anyone needs
more information please send me a message.

If needed I have a partial tcpdump of the working 4.9-PRE box with cksum
errors, but at a greatly reduced quantity.

Thanks,
Will

P.S. the lower volume was running patched sendmail that came w/ 4.6.2
(8.12.3p2 I think?). The other is running 8.12.10.

-- 
Will Froning
Unix Sys. Admin.
(209)946-7470
(209)662-4725
wfroning at pacific.edu