How to Fix Outlook.com and the Gmail Phishing Warning “This message may not have been sent by:”

At some point in my life, I associated my Gmail email address with my Microsoft Live account, so when Outlook.com rolled out, my Gmail email address was my login alias. I was surprised to see that Outlook.com let me send emails using my @gmail.com address, even though I hadn’t set it up.

I was even more surprised to see that they went through. However, there was a catch. It showed up in the inbox with a dire warning message:

This message may not have been sent by: you@gmail.com Learn more Report phishing

The problem, according to Google, was that the email said that it was coming from @gmail.com, when in reality, it was Outlook.com’s mail server that originated the message. This is a common trick by phishers, who pretend to be sending out official requests for information or login links from spoofed email addresses.

If you’ve also logged in to Outlook.com for the first time using an unrelated email address, you may also be able to send sketchy looking emails. Fortunately, there’s an easy fix for that false negative phishing alert:

• If you are trying to add Gmail to Outlook.com, use the tutorial that Brian wrote on How to Add Gmail to Outlook.com.
• For other kinds of accounts, read Send Email From Other Accounts in Outlook.com.

Note that if you are using Gmail, you might get a message in Outlook.com telling you: “Check your email address and password, but the problem may be that you need to go to Gmail’s settings page and enable “POP Download”.” To fix this, log in to your Gmail account and look for this warning at the top: “Warning: Google prevented a suspicious attempt to sign in to your account. Was it you?” Click Was it you? and follow the steps for allowing hotmail.com (or Outlook.com) access to your Gmail account.

That should clear up all your shady looking error messages in Gmail. Leave a comment below if you need more help!