Norton AV, and other email filtering and handling products which interpose themselves in as proxy servers in this way are really useless products.Equally useless, the server/gateway level, is PIX SMTP fixup.
postfix even has SMTP client hacks to workaround pix:
# postconf | grep pix
smtp_pix_workaround_delay_time = 10s
smtp_pix_workaround_threshold_time = 500s
And the PIX SMTP fixup only knows HELO (because it can't know about users+passwds), so SMTP AUTH/EHLO is not available through SMTP fixup.
They fail to implement lots of features of POP (e.g. TLS) and create serious support headaches. Products which wish to filter spam or viruses REALLY should be built to "plug in" to mail clients via APIs.Most companies don't want their employees learning how (what a laugh that is) to filter at the desktop, and then wasting $time trying to filter spam, so have implemented filtering at the MX level to keep nearly all of the crap out of the company and above off the desktop.
Len
