Rather than just the VMail feature, the Winlink/Airmail email feature, including attachments, could be incorporated. The messages could be composed while not linked to another station, essentially queued up for future delivery. Or composed while connected. Then when two stations are linked, VarAC would act as a data transport, Have something clickable to activate message transfer and then a peer to peer exchange would complete, and then drop back to standard VarAC communications when the message transfers are complete.
The host that initiates the enhanced Winlink/Airmail linkup would send a message to the partner requesting the linkup. The receiving host would just ignore the request if it doesn't have the Winlink/Airmail feature or if the feature is disabled.
This would bypass the 500 character limit that currently exists with VMail. It would add the capacity for attachments. The attachment feature could be used for ICS and ARC forms.
One thing that could be added .. unsure of this one ... is the ability to use a host as a relay for other stations. For instance, operator A could have a list of stations that it can relay for. Others can attempt to post a relay to operator A's station, but station A would only accept relay for a list of predetermined calls. Essentially a station could become a messaging hub for others.
Doug / N3JXB