"This message may not have been sent by..." warning

Why is this warning being shown?
You'll see this warning if a sender is claiming to be from Gmail, but we couldn't confirm the email originated from a Gmail sender. For example, you might receive an email claiming to be from support@gmail.com that wasn’t actually sent from a Gmail account. All mail sent from Gmail should have authentication data in the message that can verify it was sent through Gmail. If you see a warning message indicating that a message may not have been sent by a Gmail user, this means that the authentication data is missing and Gmail displays the warning for your protection.

The missing data can indicate one of the following:

  • The message was forged and not really sent by the sender’s stated Gmail address
  • The sender emailed it through a website (for example, a website sharing a news article with you)
  • The message was sent by Gmail, but the authentication information was lost (for example, if you auto-forward all messages from your school email address to your personal Gmail address)

If the email wasn't sent with Gmail, but the sender includes authentication data in the message, we'll show you the sender's name and the service that authenticated the message. For example, if sender@gmail.com sent you a card from a website called ecard.com, you'd see the sender listed as "sender@gmail.com via ecard.com.”

If I've received a suspicious message, what should I do?
Make sure that the email was sent by the sender, and don't provide any personal information or follow any links if the sender seems suspicious. You can find more tips on avoiding email scams here. If you think this is an attempt to get your personal information, click the Report phishing link in Gmail.
The email is really from the sender, what should I do?
If you're sending or receiving legitimate mail and don't want this warning to be displayed, follow the troubleshooting steps below.

The messages are legitimate, and I don't want these warnings to be shown

  • I'm receiving messages that are displaying this warning
  • I'm sending messages and my recipients are seeing this warning

How frequently are you seeing the warning message?

  • I'm seeing this warning on messages from one sender
  • I'm seeing this warning on messages from many senders

Are you auto-forwarding your messages from another account?

  • Yes
  • No

Please contact the sender or mailing list owner to alert them. The warning is usually a sign that they're not using best practices to authenticate their emails.

  • I'm unable to contact the sender

What kind of address are you sending from?

  • I'm sending from an account hosted by Google Apps
  • I'm using Gmail to send from another account

How are you sending messages?

  • I'm sending messages by logging into my Gmail account on the web
  • I'm sending messages from my mobile device
  • I'm sending messages by logging into my Gmail account from another mail client (e.g. MS Outlook, Thunderbird, Apple Mail)
  • I'm sending messages another way