I manage an (ever expanding) Exchange Server that is governed by a broker dealer and we have to journal all of our messages to an external server (emailarchive@domain.com) and we have to use their smart hosts for encryption services.
We are regularly sending and receiving 20ish MB attachments (i know i know) to and from clients. Tons of scanned PDF insurance applications. It's a PAIN but we don't have a better solution for now (that's another topic - educating our clientele).
The problem is that our journaling provider limits us to 20MB file attachments. I have limited our max attachment to 16MB....tut there is overhead associated with email attachments....sometimes 25%. So my users will send a 16MB message and it will go through to the client but will get rejected by the journaling server. then my server keeps attempting to redeliver it...