IMAP not working after installing GWAVA

[JackCunha]

BM 3.8; NW 6.5; GW 6.5. Just set up a GWAVA 4.5 SMTP scanner inside
BorderManager and before GWIA (BM now NATs the A record public IP
address to the internal GWAVA address, rather than to the internal GWIA
address). I assume as a consequence of the public IP address now
pointing to the GWAVA box and not directly to GWIA, IMAP now doesn't
work b/c it cannot connect to the GWIA ("mail.domain.com is not an IMAP
4 server"), although the IMAP to gmail still works. In another forum it
was suggested that using BM port forwarding is a possible work around:
BM 3.8 Port Forwarding?

However, this link describes the BM port forwarding workaround where
there was only one public IP address, whereas i have several, and most
importantly one dedicated to my mail. I assume that the relevance of
the TID is to the public IP dedicated to my A record which now points to
GWAVA, and no longer to GWIA? That is the public IP can again be NATted
to GWIA so that IMAP works, yet the port 25 inbound mail can at the same
time be port forwarded to the GWAVA internal address? Finally, how, if
at all, does this relate to the filter exceptions in place opening port
25 to inbound mail to GWAVA?