Rod Dorman wrote the following on 11/5/2006 9:26 PM -0800: > On Saturday, November 4, 2006, 23:14:48, Matt wrote: > >> ... Microsoft and SmarterMail seem to have >> reinterpreted the RFC's to send the 550 error as soon as the message >> goes over size, >> > > Which is wrong. > > >> and most servers do listen to such errors during the >> DATA command, but IMail doesn't. I would also like to see this changed, >> though based on my read of the RFC, IMail is not required to do so by >> standards. >> > > Where in the RFC does it state its permissible to send replies before > the completion of data transmission? > > If "Enhanced Mail System Status Codes" (ESMTP) are used via the EHLO connection exchange, then the message should be rejected as soon as the total message size is announced during this ehlo exchange and before message delivery even starts (see RFCs 1983 & 3463). That IMail does not fully support the ESMTP RFC is not good and means that system and network resources must be used unnecessarily.
Rejecting a message delivery anytime during the data stage breaks ESMTP as the sending servers will most likely interpret this as a failed delivery attempt and will re-queue the message for a future delivery, this instead of seeing it as a 552 reject and correctly interpreting it as a permanent error and sending a bounce back to the sender noting the error condition (message too large). I would expect that in this scenario some sending mail servers would continue to retry delivery until the hold time expires, meaning that the system and network resources would get reused over and over again until the message finally bounces back to the sender once the hold timer finally expires. This is not good for the sending server, the receiving server, the network, and the sender and recipient, as one thinks their message has been delivered (because the message does not bounce immediately back to the sender with a warning about the message being too large) and the other either doesn't know about the message or wonders if the sender actually sent it or not. Any way that you look at it, it is not a good situation and should be fixed. Bill To Unsubscribe: http://www.ipswitch.com/support/mailing-lists.html List Archive: http://www.mail-archive.com/imail_forum%40list.ipswitch.com/ Knowledge Base/FAQ: http://www.ipswitch.com/support/IMail/
