What to do if your email service provider is blocking our listserv postings

Back on about November 17 we migrated our listserv server from a shared-hosting server to a dedicated server.  This means that our listserv postings are coming from a different IP address now than they used to.

It seems that some email service providers have hair-trigger spam fighting systems that react in a very strong way to email traffic emanating from a new IP address.  Some of the members of our listservs have have found that some or even all of our listserv messages are failing to reach them.

if this has happened to you, there are several things that you can do to help.

One thing that you can do is to take a look at my first blog article about this (If you have stopped receiving listserv postings, November 27, 2019) as well as a followup blog article about this (Getting your listserv subscription working again, December 4, 2019).

There is a protocol called SMTP by which email servers talk to each other.  When your email server wants to be nice and cooperative about receiving an email message from somebody who is sending an email message, your email server will send a closing message with an SMTP code of “250 OK”.  The number 250 is like a smiley face.

Sometimes an email server will respond with some other SMTP code that is a three-digit number starting with 4 or 5.  This is like a frowny face, and it means the email message either will not be delivered at all or will get delayed or held up.  Usually if your email server sends a “4xx” or “5xx” message, the code will be accompanied by an explanation as to why the server is declining to receive the email message.

There is a particularly passive-aggressive thing that an email server can do which is to refuse to accept the email message and to actively refuse to say why.  This is SMTP code “550” followed by the words “Action not taken” and no other words.  And this is what we are encountering since November 17, 2019 with the email service providers of some of our listserv members.  

Clicking around on the Internet I have found articles that suggest what a person can do to try to induce their email service provider to stop blocking emails like this.  I collected the suggestions that I found, and posted them on these pages:

I don’t use any of these email service providers so I don’t have any actual experience with this.  But if you use AOL or Yahoo for your email, you might try the first article.  If you use Microsoft Outlook for your email hosting, you might try the second article.  If you use Google (Gmail) for your email, you might try the third article.

You may find that to get to where you can once again receive our listserv postings, you will have to be more pushy with your email service provider.  The worst offenders seem to be Barracuda Networks and Mimecast.  You may need to open a trouble ticket with your provider and then maybe escalate things to a supervisor, something like that.

You can get in touch with me and I can plug your email address into the logging system of our email sending server and I can generate a report that details the behavior of your email service provider during recent days.  I can send the report to you, and this might possibly help in your efforts to get your email service provider to stop blocking the listserv postings.  

Again see my earlier article here about this.  Thank you.

7 thoughts on “What to do if your email service provider is blocking our listserv postings

  1. I made changes that allowed emails from your listservs to get through for a while, but they’ve stopped reaching me again via Office 365. I’ve verified that the changes are still in place, both allowing by IP address, @oppedahl-lists.com domain as sender, and individual email addresses as sender. Any other suggestions?

    • Yes, please open a trouble ticket with Microsoft, and please escalate it to a supervisor. If it will help, I would be glad to talk with whoever you end up talking with at Microsoft.

      • I have the same issues. Will open a Microsoft ticket as well, then. see if that solves the issues. hopefully.
        but I do receive the mails about new posts from the Ant-Like Persistence mails. They come through just fine.

        • Sharon, if you opened a Microsoft ticket, it seems to have worked. I’m suddenly getting a bunch of messages on multiple listservs today. They’re all test messages, but getting them is an indication that something is working again, regardless.

  2. We use Mimecast. Though I have had @oppedahl-lists.com whitelisted, I still do not receive any of the email traffic from the list serves. I will pass this along to my IT department for all the good it will do. They are not even showing up in my spam, they are just getting bounced without asking me.

  3. Carl-
    Would you please send me an e-mail listing for my Gmail address, benappelbaum@gmail.com, so I can try to resolve this fiasco. I just set up an e-mail account with outlook.com, and would prefer to maintain gmail for the list-serves rather than to start using an additional e-mail address.
    Thanks-
    Ben Appelbaum

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