Kai Schaetzl wrote: > Sean Carolan wrote on Tue, 14 Oct 2008 08:13:34 -0500: > >> 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 doesn't really. If the OP had PMTU discovery turned on it would affect most all communications not just email. I can't ever remember having it on for external networks, there's never been a need in my case. It's just likely that the only communications between the OP's systems and the other side was email. nate