jittinan suwanrueangsri wrote, at 01/07/2009 02:15 PM: > In our environment > 1. a user can not connect to other mailserver directly such as gmail,aol > etc. except our mailserver. > 2. a user have right to use his/her other domain sender (aol,gmail) in > message which have to relay via our mailserver.if our policy allow user > to send only our sender domain we can authenticate his/her right but it > 's impossible to know which sender is his/her account in gmail or aol.we > can not connect to their database . > 3.a user need to use dynamic ip address so we can not create > allow/reject policy by source ip ,dnsbl checking or other technique base > on source ip. > 4. our mailserver is in situation same as previous post(retry > problem).There are too many emails are pending in mailserver so it > affect to other email user.email sending process is slow down because of > unnecessary retry.we sure these messages are bad .
It sounds like you (or your ISP) is blocking outgoing connections to port 25 and you are trying to get around this block or minimize its effect. If that's the case don't bother. Use your mail server to relay and handle mail for your own domain only. If users want to relay mail via other email service providers, they can use webmail or the submission port 587. Encouraging them to use your relay for domains you don't control will only complicate things and interfere with the delivery of the messages (as you seem to be discovering).
