I am seeing this error only on new user registration, but the email is sent successfully .

I am using SMPT authentication.

Could this be a permissions issue as this is the only time the site sends mail to an anonymous user?


I dont know why this might happen. You may need to add a bit more detail so someone can help.

Yes its odd.


I have identical sept configuration with Drupal 7 and all is fine, but if I use SMTP Authentication on Backdrop I get error this error message. 


I would be happy of I could just suppress the error messages because the mailing works fine




Actually I meant a bit more detail about your situation: what do you mean about SMTP, the contrib module or your server mail configuration? Is this a live site, any details about your setup? What is the exact error message? Is it in the logs or on screen? Do you get this error constantly? How about when you create a user yourself vs when a user signs up?

p.s. I may not be able to help you but details help those who can, to help.

Wow. I didn't expect that level of support!! Very grateful


I will give full details ASAP



The SMTP is setup using the contrib module (and mailjet)

The error message is "Unable to send e-mail. Contact the site administrator if the problem persists"

It is a live site on www.tredegarhouse.com

The hosting is with DigitalOcean

The error also appears when admin creates a user account, but the odd thing is that there is no problem when a user requests a new password.

Backdrop is a perfect soltion for me..I was about to abandon Drupal because I simply could not adapt Drupal 8 to my (relatively simple) needs.


drop's picture

It looks like your issue may be related to this one: https://www.drupal.org/project/smtp/issues/1491914

From the comments there, It sounds like some hosting companies don't allow relaying, or because some ports are blocked. Here are a few fixes that worked for others:

* Use Transport Layer Security (TLS) 

* Use port 587 (if its not blocked)

* Set the Contact module "From" address to the same address as the "Site Mail" address (if you are using the contact module?)

There are a few more technical suggestions in the Drupal issue, but it might be good to call your hosting provider and ask what they recommend instead of playing the guessing game :)

Good luck!

The error seems to be that the site is trying to send send an email back to the site administrator.

Since the email is functioning perfectly ...I would like to comment out the line that reports this error which used to be in mail.inc (not perfect I know)

Where is it in backdrop??






drop's picture

I wouldn't recommend commenting out the line that generates the error. Not only will you not see the error message when you are having a problem, but also any changes you make to core are likely to be overwritten when you apply the next core update.

It would be much safer to get to the root of the problem, solve it, and prevent the error from appearing for this particular instance of the error (only).

That said, If you are prepared for the consequences of hacking core, I recommend documenting your changes in a PATCHES.txt file, like Jen describes here.

I often find the line of code that's generating an error by searching the codebase for the exact error.

grep -R "Unable to send e-mail. Contact the site administrator if the problem persists" .

This returns mail.inc for Backdrop as well as Drupal.


If I check  "Send mail by queue" in SMPT authentication, the problem goes away. It means I have to rely on cron to send emails but I can live with that.

Thanks a million for your input.