Broken e-mails when using Mailgun API

  • Joakim

    (@noboxjoakim)


    1 month ago

    We have suddenly gotten a lot of headache when using Post SMTP in combination with Mailgun API. From having near perfect e-mail deliveries according to mail-tester.com we were suddenly down to a horrible 1.9/10 score and started getting e-mails ending up in junk across Gmail and Microsoft recipients.

    After looking through all kinds of DMARC, DKIM and SPF-records according to the suggestions from mail-tester.com without any luck I started experimenting by replacing Post SMTP with another SMTP plugin. With that single change, we went from a 1.9/10 score to a 9.8/10 score on one of many affected sites. No other modifications made, only replacing Post SMTP with another plugin.

    Compare https://www.mail-tester.com/noboxsolutions-ZBTF with https://www.mail-tester.com/noboxsolutions-WHBD to see for yourself. Unknown how long lived the links are.

    This is potentially a huge issue for a lot of plugin users and could possibly affect other tools besides Mailgun as well. I have tried Post SMTP versions 3.9.1, 3.9.0 and 3.8.0 with the same results. Please look into this and if you need any further details, do feel free to reach out to us.

Viewing 5 replies - 1 through 5 (of 5 total)
  • Plugin Support M Aqib Khan

    (@aqibkhan9)

    1 month ago

    Hi @noboxjoakim ,

    Thank you for the detailed report.

    We’ve escalated this to our development team for investigation.

    If possible, also let us know:

    • Which Mailgun region (EU/US) you’re using
    • Whether you’re using API or SMTP mode

    We’ll prioritize this and keep you updated as soon as we have findings.

    Thread Starter Joakim

    (@noboxjoakim)

    1 month ago

    We use EU and API mode. I can look around and see if we have any US based setups as well.

    Plugin Support M Aqib Khan

    (@aqibkhan9)

    1 month ago

    Thanks for confirming.

    Thread Starter Joakim

    (@noboxjoakim)

    1 month ago

    @aqibkhan9 Any updates on this? So far I have had to replace Post SMTP on a number of sites to get the e-mails running again. Would prefer not to have to do that across all that has Post SMTP running.

    Plugin Support M Aqib Khan

    (@aqibkhan9)

    1 month ago

    Hey @noboxjoakim

    Thanks for following up.

    The case is currently under review with our internal team, and they’re actively investigating it. As soon as we have a concrete, shareable update, we’ll reach out to you here.

    Appreciate your patience on this, we understand the impact and are treating it with priority.

Viewing 5 replies - 1 through 5 (of 5 total)

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