Does every client use a different login?
You could create a table with one record for every Account Name and then you create additional fields for any setting you would like to link to this account.
Smpt settings, email address, ...
Kind of like a settings table.
Then when you run a script to send an email you could have a temp field where you set the current account name and that field is related to your "settings" table and there you can get the correct smtp info for that account.
Damn, I'm clever :p