[quote user="Dustoff"]Yes, I can list many identities in the SMTP network configuration and switch between them by using the disable/enable buttons on the right side to choose the one I wish to use at the moment. It does NOT matter where that identity is in the list if it is the only one enabled. Perhaps if I moved the desired one to the top of the list that would work as well but I have not tried it since I feel more comfortable disabling the ones I am not using.[/quote]
Go to Tools / Identities and create a new Identity and then 'become' it. Now set up the SMTP setting you want for that. This will be activated every time you become that identity - there's no need to enable/disable items each time. You can set the shortcut to start in a specific identity or change manually after starting. There are quite a few options which are identity-specific, including your email address.
[quote]Neither the manual nor the help files describe the way to choose between multiple SMTP identities and I had to figure it out for myself.[/quote]
The help has a detailed section on Identities and Attaching identities to folders. It doesn't mention SMTP explicitly, but does talk about different POP3 definitions.