I have a question about the Mail Sentinel AV and probably about the SMTP
proxy in general. Does GTA's implantation of the SMTP proxy properly
support ESMTP commands (Especially AUTH). Most proxies I have dealt with
seem to ignore/change this command (Cisco's SMTP fixup for instance
changes AUTH into NOOP and changes the return OK into an error).



The reason I ask is because we host e-mail services, but we're not an
ISP. This makes it difficult to restrict legitimate senders by IP range.
We've found ESTMP-AUTH to be the best solution (Unless somebody knows a
better one?) for us. However, due to most proxies trashing ESMTP
commands (From what I understand, Cisco's stance is that ESMTP is a
security risk), I fear to use any sort of proxy on our SMTP. I think I
can still work something out however even if ESMTP won't work through
the proxy. According to RFC2476, port 587 should be used for users
submitting mail into the network. This means I could leave a
proxy/scanner on port 25 to scan everything coming into our network from
the outside (and scan all outbound if it works that way...). This isn't
the ideal solution however since I've found that many pieces of software
that can submit e-mail but aren't really e-mail clients don't like
sending SMTP anywhere but 25. It would also prevent me from checking
'internal' users for viruses.



Additionally, is the AV scanning done on both inbound and outbound
e-mail?



Christopher Congdon

Network Engineer

Congdon Web LLC

317-920-9601

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