Is there anything relavant in your error_log files? Where is this message coming from?
Hello @pacmanfan ,
We hope this message finds you well.
Thank you for reaching out to our Support team. We’re truly sorry to hear that you’ve encountered this issue.
To assist you effectively, could you please share the error message from the Mailgun’s email log with me?
Looking forward to your response & an opportunity to assist you.
Warm regards,
Support Team – WP Experts
There are no logs on the Mailgun side–as far as I can tell, it is not making it far enough to show up on their side.
The email is coming from the site admin email address, so I guess it’s being sent by mail(). The error in error_log is:
ERROR PostmanWpMail: Exception code=0 message=Code: , Message: , Body:
Looking farther back in error_log, I can see that multiple sites with this error have been giving a different error almost daily, for a long time, but we aren’t aware of any email deliverability issues in spite of this error:
FATAL Postman: Postman: wp_mail has been declared by another plugin or theme, so you won't be able to use Postman until the conflict is resolved.
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This reply was modified 3 months, 1 week ago by
pacmanfan.
Hey @pacmanfan,
Thank you so much for sharing the error with me. The error “wp_mail declared by another plugin or theme” indicates a conflict with another plugin or theme. To identify the source, kindly carry out a conflict test by switching to a default theme and disabling all plugins except Post SMTP. Then, reactivate them one by one until the conflicting plugin is pinpointed.
As for the email error, please log in to Mailgun’s dashboard and check the status of the emails that are marked as failed in the Post SMTP Email logs. This will provide us with comprehensive insights into the exact cause of the issue.
Looking forward to your response.
Warm regards,
Support Team – WP Experts
I’ll work on isolating where the conflict is coming from, thank you.
Mailgun logs are not showing any sent messages on our sending domains that are using Post SMTP after this error started with the 3.4.2 update. I think the plugin is not successfully making a connection to Mailgun to attempt to send the message.
Hey @pacmanfan,
Thanks for confirming. To further narrow down the issue, please try rolling back Post SMTP to a previous version and test email with the same configuration. This will help us confirm whether the issue lies with the configuration or the plugin itself.
Warm regards,
Support Team – WP Experts
I rolled one site back, by uploading the installation archive for the older version and selecting “Replace current with uploaded” when it asked. I tried 3.4.1, 3.4.0, and 3.3.0, and am still getting the same error when sending through Mailgun.
Hey @pacmanfan
The issue seems to be on the Mailgun’s side. If you could create new API key & try with the latest version.
Let me know how it goes.
I have tried it with a new Mailgun API key on two sites, and am still getting the same error on both. Thanks for your attention to the problem so far!
Hey @pacmanfan,
Apologies for the delay in getting back to you. We tested the Mailgun API on our end, and it appears to be working as expected.
If you’re still experiencing the issue, I’d recommend opening a support ticket on our official site so we can provide you with more prompt and detailed assistance.
Thank you sincerely for your patience and cooperation.
Warm regards,
Support Team – WP Experts
This turned out to be a firewall issue with our shared hosting provider.
