today received info from msgtag support . They say
"In MSGTAG (Options->Tools->Mail Accounts then select your Mail Account from the list and click "properties")
SMTP Server: (your ISPs SMTP server)
SMTP Port: 25
Listen for MSGTAG Connections: 7362
In your mail client (Vista):
Outgoing SMTP Server: 127.0.0.1
Outgoing SMTP Port: 7362"
Haven't tried it yet, but that 127.0.0.1 was another of the settings that puzzled me and those who helped me with my connection problem.