[Tickets #4814] Re: vlad.horde.org timeout after EHLO

[bugs@bugs.horde.org]

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Ticket URL: http://bugs.horde.org/ticket/?id=4814
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 Ticket             | 4814
 Updated By         | cbs at cts.ucla.edu
 Summary            | vlad.horde.org timeout after EHLO
 Queue              | Horde.org Servers
 Type               | Bug
 State              | Accepted
 Priority           | 2. Medium
 Owners             | 
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cbs at cts.ucla.edu (2007-01-15 14:18) wrote:

Anything that is short and keeps packet sizes under 1480 will come through.
 Mail generated by hand (either telnet to port 25 or using "mail" or
"sendmail" or whatever) is generally going to be mall enough due to a lack
of normal amount of list-related headers.

The problem is caused because a) something (either directly on coyote and
vlad, or something in the network) is filtering ICMP traffic, and b)
something in the network path has an MTU of 1480.  Because of the ICMP
filtering, ICMP MUST-FRAGMENT isn't being sent, breaking PMTU.