I have been using Google groups for quite some time. Recently, when I'm viewing the mails from these groups I get warnings on the header saying:

This message may not have been sent by [email protected]

I'm mostly using the groups for discussions, so I don't really care. I just don't want anyone to get that warning when I send a message to the group. How do I go about that?

What should I do so that whenever I send an email to any of the groups, another user of this group doesn't get this warning?

3 Answers 3


Google says your options are:

  1. Send your mail through their SMTP servers (i.e. don't use Gmail's web interface)
  2. Get the admin of your mailing list to set up authentication (I have yet to find a description of what this actually entails.

As far as I know, there's no way of turning these off for mail from other gmail users - unless the mail came directly from them and not through an intermediary, the warning will be displayed.

http://gmailblog.blogspot.com/2011/06/protect-yourself-from-scams-by-knowing.html explains the changes. Hopefully, they will improve the format of those messages for mail that goes through a mailing list.


The warning is generated based on very broad statistics - techniques used by phishers almost always include sending from spoofed email addresses, so this is generally a good indicator of phishing activity (when combined with other points)

Unfortunately, as you have seen, there are perfectly valid reasons for mail to appear to come from an address other than that stated, but that would presumably be quite a bit harder for Google to build rules for.

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