Can I run more than one copy of CustomMailer on my machine at the same time?
No. In order to protect you from conflicts between two simultaneously running copies of CustomMailer that could affect your data and/or email integrity, CustomMailer has a test that prevents you from starting up more than one copy of CustomMailer. If CustomMailer is already running and you try to launch another copy, this will bring your already running CustomMailer window to the front.