E-Mail Comment Notifications on Multi-Sites not working for Sub-Sites

I am not sure if my problem is exactly the same as the one mentioned here (https://premium.wpmudev.org/forums/topic/e-mail-notification-for-comments) by EJarolim, but its effects seem very similar.
I now tested, if comments work on pages, as I normally do not allow comments there. But those have the same problem, though I think I got those longer than the comment notifications. (I can’t check that, because a computer crash swallowed some of my not saved mails.)
But I get mail from contact forms and other alerts from the page, just no comment alerts. Those also do not go out to the comment poster, though I would have installed a plugin to get alerts for responses.

On some websites of mine, everything is fine and on two others that just won't work. As they all are on the same server and in the same service of the hosting provider, I can't detect any difference there.
I already tried to deactivate all plugins, but that won't change anything, as far as my tests revealed.
The two sites where the comment alerts are not working, are both Multi-Site installations and the comments would be on sub-pages, where the normal alert and contact mails from form entries work.
For one website, I have a catch all mail address and for this one I got strange error messages. It is as if mails were sent from an address for my website, which does not exist, as WordPress seems to create a mail address after its own logic, like
The mail address obviously does not exist that way and was never entered by me in that form. I also have no idea where it is mentioned like that, because I could not find it anywhere in the backend, where my normal mail address is everywhere I could find a mail address entry.
But it seems, WordPress has a kind of logic for MultiSite installations since a few updates of WordPress back, because before everything seemed to work fine. But now, it seems to self-create mail addresses for the comment notifications. I searched, but still I could not find out where I could influence those used mail addresses for the sub-pages. My best guess is the information stated in the network-admin site settings, where the information is:
Mail-Server : mail.example.com
Mail-Server login: login@example.com
But here I am not the least sure what I will influence here or how the correct setting should look like.

The website seems to send mails correctly, where the sender mail can be clearly defined or takes the admin mail address. But everything else automated seems to not work properly on the sub-pages, as the comment notifications try to use a non-existent mail address.
After I entered the code for PHP-Mail in the .htaccess
php_value mail.force_extra_parameters –fwebmaster@example.com
I got the error messages I usually got for comments on the website with the catch-all mail address also for this site, so at least that seems to catch the messages now somehow, though the error with the wrong sender mail still exists on both websites.
I tried to install the suggested SMTP plugin (WP Mail SMTP), but the test mail for the plugin already gives back the usual error that the sender mail wordpress@subpage.website.com causes problems, though I specially entered the access settings for my e-mail, which should be used as sender address, but those settings are ignored.

I am a bit at a loss now, where I could continue my search for a solution now and would really appreciate, if you could help me with this error. Thank you very much in advance !

  • leejacksondev
    • Site Builder, Child of Zeus


    Am I right in thinking this is:

    1. Install of wp multisite
    2. As default core site and some sites seem to work sending comment notifications
    3. Others don't seem to work
    4. Gauging if they worked means checking your inbox/spam folder to see if you receive any

    Regards SMTP, if you are already getting some messages I doubt you need to try an alternative method of sending.

    It could either be config of those sub sites, or alternitavely your spam folder playing tricks on you?

    I admit I skimmed... if you could write that in less words I might be able to help better

    Screens of your settings on a working site and a non working site might be helpful


  • RGerhart
    • Flash Drive

    Thank you very much, leejacksondev.
    I tried in less words, I just tried so many things already and wanted to give you a hint about those, not to lead you into a direction I had already tried and ruled out.

    The spam folder unfortunately is not the solution, as I check that regularly.

    To 1 and 2: Yes, both problematic sites are Multi-Site installs, but so are others that work (Though those are still only the main site without sub-pages, so I have no complete comparison here).
    To 3: The form entries (where the sender mail seems to be directed to the admin mail or a manually given e-mail address) work, but all the comment alerts don't work from the sub-pages.

    What setting screen shots would you need?
    I already compared the working and not working sites for hours and did not come up with anything different, though I have other plugins installed, but as deactivating them did not change anything, I am still not sure that is the solution.

    I could send you an error message for an undeliverable comment notification. Perhaps that could help?

    Thank you very much for your help !

  • RGerhart
    • Flash Drive

    Hello Patrick,

    Just saw your message about the hosting plans.
    I have the websites on a managed server in separate sections, but with the same hosting plans. Only one of the not working WordPress websites is together with other installs, which could influence it. The other one is in a separate sector (hosting plan) on its own.
    I hope that helps you, though for me it is rather irritating.

    Thank you for your help !

  • RGerhart
    • Flash Drive

    Hello Patrick,
    Thank you very much for coming back to this topic.
    I still could not solve the problem with the comment alerts and don't know what to do to get closer to a solution.
    So I really could use some help with it.

    Thank you very much for coming back to my question.
    If you need further or other information, please let me know.

  • Patrick
    • Support Monkey

    Hi again @RGerhart

    I just re-read your original post and think I may have found a clue :slight_smile:

    You mentioned that in your network settings, you see the following:

    Mail-Server : mail.example.com
    Mail-Server login: login@example.com

    There is no default WordPress setting that refers to mail-servers. Is it possible that coming from a SMTP plugin you have activated on those networks?

    Have you double-checked the settings of that plugin (whichever one it is)?

  • RGerhart
    • Flash Drive

    Hi @Patrick Cohen
    Please excuse my late reply. I had overlooked the alert for your message.

    In an effort to repair the existing mail error, I had installed the plugin:

    Though I am not entirely sure the error really lies in an SMTP-problem. The mail address the website tries to use to send the mails does not exist, so I think the problem happens earlier than the error-reason given in the mail-error alerts.
    Example of such an error header here (I changed the mail address to be neutral):

    SMTP error from remote mail server after MAIL FROM:<wordpress@subsite.website.com> SIZE=2756:
    host []: 550-Verification failed for <wordpress@subsite.website.com>
    550-Unrouteable address
    550 Sender verify failed

    The mails from the website sent for form entries and e.g. the contact form work perfectly, as here the mail address to use for the sending of mails is clearly defined and exists, while the automatic mail alerts, e.g. for comment notifications, just use imaginary non-existing mail addresses on the sub-websites in the MultiSite of the WP environment.

    Best regards,

  • Patrick
    • Support Monkey

    Hi again @RGerhart

    Geez, this one is really taking a long while to resolve. :slight_frown:

    You are actually quite right about the MailServer settings in the network admin. I seem to have overlooked that earlier

    To test the theory of undeliverable mail, I set up a new multisite install on the same server as my other test sites. Then ran the E-mail Address Trace in cPanel for that site on my own address. This is an example of the error I got from that report:

    SMTP error from remote mail server after initial connection: host gmail-smtp-in.l.google.com []: 550 significant abuse from this ip

    Very similar to yours, yes?

    I also noticed that only Google (gmail) bounces emails in that manner.

    Have you noticed any similarities or pattern in the destination email addresses that don't get delivered?

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