[CentOS] Sendmail and pmtu discovery

Les Mikesell lesmikesell at gmail.com
Tue Oct 14 15:09:18 UTC 2008

Kai Schaetzl wrote:
>> My mail logs are showing that customers who specifically disallow ICMP
>> traffic have many "Connection Reset" entries in our logs:
> Could somebody explain why ICMP might play a role in mail delivery?

It is required for any TCP conversation, unless as a matter of luck you 
happen to have the same MTU capability across the whole path - or the 
end points restrict their MTUs arbitrarily to a size that everything can 

   Les Mikesell
    lesmikesell at gmail.com

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