I'm having problems with any attachments over 1MB being "deferred" "Sender Timeout" on my Barracuda. I didn't have this problem until about a month ago. As far as I know nothing has changed on my firewall or barracuda in quite a while.
I called Barracuda Support and they told me I need to port forward my Watchguard to the Barracuda. In other words the Watchguard was still answering the HELO. As far as I can tell I've already done that but obviously I'm missing something. I've attached what I have for SMTP in my Watchguard.
I don't think it is the firewall that is causing the problem but I need to complete this task before they will help me.