Error testing Bounce email using SMTP from hosting provider - Other SMTP Server

Hi I’m running a hosted Mautic 4.3.1.
I’m having a problem that might not have to do with Mautic, or maybe, but would like to know if someone has had it and how it was solved.

Naturaly I searched through the forums, and have not found a post that would help to solve my case.

I have configured the email settings in Mautic and the “Test Connection” button gives a Success message.

However when I try the “Send Test email” button I get the following error message:

Expected response code 250 but got code “550”, with message "550 “The envelope e-mail address does not exist” "

This may be a problem with the provider or Mautic, is there anyone who can help and give a hint on how to overcome this problem ?

Additional information:

  • Previously to Mautic i was using Phplist and sending emails without problem using the same mail account.
  • In Monitored Inbox Settings when I click on the “Test connection and test folders” button I also get success message.
  • If I remove configuration from “Custom return path (bounce) address” in “Mail and settings” and all configurations from “Monitored Inbox Settings” and click the “Send Test email” button, it works and i get the test email.

Hi @peteredhair

You should try a simple email like as it is likely that your email does not support additional accounts by adding any valid string of characters after a “+” like the one you indicate:

Such “additional aliases” are usually supported by services such as Gmail, etc., but not necessarily by your domain.

I don’t think it’s a problem with Mautic but with your mailbox.


Thank you very much for your reply.
I also believe so.

However, while reviewing the configuration of the mailbox i found the following information where it refers to addressing with the + sign.

I’ll follow on the provider side as they are open to investigate, although not knowing, yet, the reason that triggers the problem.

Once again, thanks for replying.


Automatically Create Folders for Plus Addressing Automatically create a folder when this email address receives a message that uses plus addressing. For example, the system would place a message addressed to “” in a new folder called “plusaddress”.

Automatically Create Folders is selected, will try with not creating folders automatically with the + sign.

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Just to add a new note.
If an email is sent to the mails is received, in the bounce folder.

If you do what you say and your mail client does not support plus (+) addressing, as for example Gmail does, then this is the response you will get from the remote server when sending mail to that address:

550 <> sorry, no mailbox here by that name. #5.5.1


Hi gnumax,
thank you for your reply.

Tested, before your post, and the mailbox works with the + sign.
The error only occurs while configuring bounces in mautic email settings.

I’ve been trying and searching and have reinstalled phplist just to make sure my previous information about having this working with phplist was correct, and yes it was.

I believe it’s some setting in mautic as i have tested the mailbox with the plus + sign and it works, as i’ve said in my previous post.

And now it’s really bugging me as this is the beginning for everything mastic.

If i don’t configure anything related to bounces, no problem, but bounces processing is an important part of the process and also an important part of establishing spam score credibility.

So I’ll keep digging but probably for the moment will be back to phplist, until i or someone figures out what is the problem, so that i can solve it.

The error message reported at the beginning of this thread, regarding bounce configuration:

Expected response code 250 but got code “550”, with message "550 “The envelope e-mail address does not exist” "

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Instead of messing around with more tools, like phpList for example, I prefer to manage separate mailboxes, and this gives me a more granular control of the email process.

And I avoid the mailbox aliases


Thanks for the advice but that has already been done.

Mautic states on the configuration page that it uses the + sign.

Phplist works with the same mailbox I’m using for nautical and doesn’t have this issue, as it doesn’t require the usage of the + sign for bounce configuration and processing.

Hi @peteredhair

I recognise that sometimes Mautic does strange things and maybe that’s why you are not getting the + parameter in an email when Mautic processes it.

I have a similar problem with links that incorporate & in the link that Mautic replaces them when it receives them and then they don’t work when it delivers them modified to the contact.

I still think it is a “bug”. :thinking:

Sorry I can’t help you better! :roll_eyes:

Thank you gnumax,
looks like i’ll have to upgrade to see if this difficulty disappears :wink:
Thanks for your replies.

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