问题
While it was possible to use Gmail/Google Apps as an SMTP server for scripted use or in any other Apps. I started getting error messages:
SMTP Error: 454 4.7.0 Too many login attempts, please try again later.
Sometimes you get, sometimes you don't get such error.
回答1:
The issue is because of Google Apps Security. You Can't use same E-mail ID with more than 2 Apps. as Gmail needs to sync it, and it is Obvious to receive such error.
Even setting SPF/TXT/DKIM record is not enough for it.
So try to use different E-Mail IDs for Different Apps.
来源：https://stackoverflow.com/questions/34921053/gmail-app-google-smtp-error-454-4-7-0-too-many-login-attempts-please-try-ag