I've run into some problems with using Amember on my Linux host. I deliver almost 27,000 newsletters every two weeks, and that is a challenging problem for email relays and server support. Last week, the send disabled my entire system's email for a few days while the host figured out what I'm doing. Ideally, I could setup Amember to use 1 email account (probably php mail) to send out all system-related emails (login requests, payment receipts, whatever) and a different one (probably external smtp host) for when I email my userlist. I could then direct the newsletter to a smtp service that can handle my volume without impacting my ongoing server operations.