Does gmail avoid from some emails even to be in spam box? [closed]
gmail has strict e-mail policies and they do indeed reject a lot of e-mail before it even enters the system.
Especially if we are talking bulk e-mail such as newsletters and such. Google has a lot of advice listed here: https://mail.google.com/support/bin/answer.py?answer=81126
Also they most likely (like most other large e-mail providers) have some internal rules that are not public, which can cause e-mail to be rejected.