I understand that Gmail groups emails together by subject for its conversation view. I get it, I love it.

I am a member of a Google Group that receives an email at the same time every day, and these are forwarded to my individual email address instantly. The email sent to the Google Group email address is identical: same sender, same subject, same body (from an automatic process). When I receive these emails each day in Gmail, they are not grouped together in a single conversation, but rather fill up my inbox with individual messages. The emails are precisely 24 hours apart, so I doubt that they aren't being grouped because of a lengthy time gap. The email subjects don't include any "Re:" or "Fwd:", however I've sent emails from one of my accounts to another with the exact subject used from these emails and the 3 I tested grouped together into a single conversation with 3 emails, but again, did not group to the existing email messages that came from the Google Group.

Are there any other criteria for grouping that would be causing these to not get grouped together in a conversation?

I've tossed two of these emails into a diff program and compared what is different. My understanding is the subject is what matters, and that is identical though.

  • Received: (appears several lines, ip, SMTP id, and +addressing string are different)
  • X-pstn-nxp (different bodyHash and headerHash)
  • Authentication-Results (contains different +addressing string)
  • Return-Path: (the email back to the Google Group has a different +addressing string)
  • Received-SPF (the email back to the Google Group has a different +addressing string)
  • Message-ID

Sending myself an identical email message from one of my emails to the other, 21 hours account did not group. So...I guess is there anything I can do to make these group into a conversation?

  • These once-a-day emails, do they have the same subject line?
    – jcolebrand
    Jun 29, 2011 at 3:17
  • 2
    @jcolebrand, The email sent to the Google Group email address is identical: same sender, same subject, same body (from an automatic process). Jun 29, 2011 at 3:20
  • Being 24 hours apart might have something to do with it. Sounds like too long to group. Jun 29, 2011 at 4:21
  • @EightDaysofMalaise, unfortunately I can't test that quite yet. (; Jun 29, 2011 at 4:23
  • @EightDaysofMalaise Nopes, that isn't it. Jun 29, 2011 at 16:03

4 Answers 4


As a bit of a spoiler, we tested this last night. I have two email address (which I will call for the sake of example "[email protected]" and "[email protected]"), and then we did this:

To:      Rebecca <[email protected]>
From:    My Name <[email protected]>
Subject: this is a test
Body:  blah blah whatever

and additionally

To:      Rebecca <[email protected]>
From:    My Name <[email protected]>
Subject: this is a test
Body:  this should nest under the other

and voila, they nested. No work required. And then we did this:

To:      Rebecca <[email protected]>
From:    My Name <[email protected]>
Subject: this is a test
Body:  does this nest with the others?

And it didn't nest!

So in other words, two emails from the same sender with the same subject will nest. Two emails from two different addresses with the same subject will not nest.

  • But based on the headers that are different that I edited in to my question, this doesn't seem to be what's up? Jun 29, 2011 at 16:40
  • 3
    The test doesn't match the use case of the same sender, body and subject not nesting Jun 29, 2011 at 16:46
  • I just wanted to point out that "same subject" is not sufficient to coalesce.
    – jcolebrand
    Jun 29, 2011 at 16:49
  • 1
    @Eight body never had to match. But these emails didn't have all the additional headers of Rebecca's further research that she has at the bottom of her post. I wonder if having those would change this scenario.
    – jcolebrand
    Jun 29, 2011 at 16:54

Google does not currently offer any way to improve their conversation groups/breaks. https://support.google.com/mail/answer/5900 implies only subject is utilized in making this decision, but both you and I are finding that's not the case.

A conversation breaks off into a new thread if the subject line changes or the conversation reaches more than 100 messages.


Mail Settings > General tab > Conversation View area > Conversation view off

To ungroup your messages, log into your Gmail account on the Web, click on the gear icon in the upper right corner and choose Mail Settings. On the General tab, in the Conversation View area, click the button next to “Conversation view off” and then click the Save Changes button at the bottom of the settings page.

  • 1
    I don't see how this answers the question.
    – ale
    Sep 1, 2013 at 13:39

We have a similar issue, emails with exact same subject, same/diff day, various senders, generated by our Helpdesk platform as HD ticket updates, do not get threaded as a conversation.

I think what is missing is that the 2nd and subsequent emails do not have "Re: " as the prefix of their subject, but that's just a Wild-A$$ Guess. Google probably received complaints about emails from service accounts or coming in from web forms where the sender is constant but the read customer name/email is in the body of the message (formatted by the web form) were getting threaded into long threads of unrelated messages, so at some point they tightened the threading rule to require the "Re:" reply flagging. When we first went live with Google, we had to have dozens of web devs change their forms pages code to add a datetime or other unique string at the end of the Subject to force non-threading, but under the current (late 2018) rules, that might not be necessary. I know Groups as recently as mid-2018 had the opposite problem, threading by Subject alone so we had to fiddle around with how the Subject was set coming out of CRM (we added their name or email at the end I think), to get each inbound "support case" to be treated as separate threads in Google Groups when they replied to the CRM automated notifications with specific questions.

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