I'm trying to configure my Gmail account so that I can use it to send mail as my Microsoft address (let's say it's
firstname.lastname@example.org), but I'm getting a weird error.
I've already gone into Gmail's Settings > Accounts and Import and added the Hotmail address under the "Send mail as" section, using server
smtp.live.com, on port 587 with TLS. Gmail is now asking me to verify that I own the Hotmail address via an e-mailed code.
Unfortunately, every automatic verification mail that Gmail sends to
email@example.com results in this:
Delivery to the following recipient failed permanently:
Technical details of permanent failure:
Google tried to deliver your message, but it was rejected by the server for the recipient domain hotmail.com by mx4.hotmail.com. [18.104.22.168].
The error that the other server returned was:
550 Requested action not taken: mailbox unavailable
----- Message suppressed -----
The exact Hotmail server varies but the message is otherwise the same.
Some quick searching shows that a 550 error usually results when an e-mail address is entirely invalid, as would happen if the account didn't exist. However, I can log into Hotmail as
firstname.lastname@example.org and when I manually type up an e-mail in Gmail and send it to
email@example.com, it goes through just fine.
What can I do to finish setting up this mail alias?