Gmail – Limitations on Sending Email Through SMTP

I think something is off with your university's mail system. I've tried sending mail using a custom From address and an incorrect password and it's been my experience that Google's mail system tells me that the remote server rejected my credentials via an error message delivered to my Gmail inbox. For example:

Delivery to the following recipient failed permanently:

<email address>

Technical details of permanent failure: Google tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error. The error that the other server returned was: 535 SMTP AUTH failed with the remote server. (state 8).

Two things to try out: 1) Run a quick test in Thunderbird Portable to see what sort of error message might come back from your school's server if you send it incorrect credentials. 2) Contact the IT department and ask them if you should be receiving errors from their system.

It's also possible that you have a filter that archives or deletes messages matching some criterion that Google's errors happen to share. Give your filters a once-over just in case.

Alright, I figured one way to do this. In order for this to work you need an email account without an @gmail.com address. I used a Google Apps account, but another service provider's should be fine as well (e.g. @yahoo.com, @hotmail.com, etc.). The key is, that when you press the "Next Step" button in the "Add another email address you own", it must ask you the "Send mail through your SMTP server?" question. If it does not, you must use some other email provider.

Here are the steps:

1. Press the Send mail from another address button.
2. For the email address, enter in a non-gmail address that you own. It doesn't mater which one you choose, no one will see it. The only thing that is important is that you can access it.
3. Press Next Step.
4. Choose to Send through [domain.com] SMTP servers.
5. Enter in the credentials for the other gmail account you want to send as:
   • SMTP server: smtp.gmail.com
   • Username: example@gmail.com (the other gmail address you want to send as)
   • Password: (the password to login to the above gmail address)
   • Use SSL
   • Port: 465
6. Press Add Account
7. Verify the address by clicking on the link that was sent to you.
8. Send an email message, and choose to send it as that temporary account from step 2.

Even though you chose to send as the address from step 2, it will appear as the email address you chose from step 5. This is more of a temporary workaround, since this seems like a bug in Gmail, which may be fixed sometime in the future.