I am running SBS 2003 with Exchange Server 2003 built-in. I have read the MS KB article at http://support.microsoft.com/kb/322679
and so I have checked every possible place in Exchange where a mail size limit can be set and I have no limits anywhere. I am sending mail to an external test account which has a statuatory mail limit of 3.5 Mb. I have just checked with my business broadband provider and they have a mail limit of 50 Mb so as far as I can see there should be no problems.
The test attachment I am sending is a 2.5 Mb Autocad drawing file and when sending it I receive the standard delivery failure notification message
This message is larger than the current system limit or the recipient's mailbox is full. Create a shorter message body or remove attachments and try sending it again.
<#5.2.3 smtp;450 5.2.3 Msg Size greater than allowed by Remote Host>
If I send a message with a 1.9 Mb attachment it goes no problem and when I look at the external mail account it shows the total size of the message as 2665K.
Any ideas? Is there a hidden limit on attachment sizes somewhere? I have a firewall but as far as I can see it is not set to block attachments of any kind or size.