I recently replaced several of our printers with Lexmark X548 multi-function units. I finally got a chance to setup scan to email and hit an all to common bug. We use Google Apps for Business and no
matter what settings I tried, I could not for the life of me get authentication to work. I kept getting 530 errors. Finally I found a post on a unrelated printer suggesting I try a Google SMTP server I had never heard of: aspmx.I.google.com.
Using the following settings, it works perfect.
Primary SMTP Gateway: aspmx.I.google.com
Primary SMTP Gateway Port: 25
Use SSL/TLS: Disabled
SMTP Server Authentication: No Authentication Required
Device UserID: email@example.com
Device Password: password
Hope this helps someone!