Mail Servers

[Ghetti, Ron]

ok, slightly off topic but our mail server is suffering 
transferis interuptis only with comcast servers over the past few weeks.
 
running postfix  + mailscanner on ubuntu linux
 
reasonably current on everything, this is something that just started, 
appears to possibly be my firewall doing the interupting but I'm not convinced.
my logs say lost connection after Data.
 
I know this is pretty general but wondering if anyone has run into something similar ?
 
 
much thanks
 
-Ron