Question Plesk / msmtp – SMTP 501 error when sending system emails via IONOS

[sauerleander]

I’m having an issue with outgoing system emails on a Plesk server using msmtp.



Emails are sent via a subdomain, using IONOS SE as the SMTP provider (smtp.ionos.de:465).



The following error occurs:

host = smtp.ionos.de:465
tls = on
auth = on
user = psaadm@panel.example-domain.tld
from = root@panel.example-domain.tld
recipients = root
smtpstatus = 501
smtpmsg = "501 Syntax error in parameters or arguments"
errormsg = "recipient address root not accepted by the server"
exitcode = EX_DATAERR

It appears that the SMTP server rejects the recipient address root, while authentication itself succeeds.



Has anyone experienced this with Plesk system mail or msmtp when using IONOS SMTP?

What would be the recommended way to handle system recipients in this setup?

 

[Sebahat.hadzhi]

Hi, @sauerleander . Could you please navigate to Plesk > Profile & Presence. Make sure that administrator e-mail address is specified in Email Address field and press Apply.

 

[sauerleander]

Hi, @sauerleander . Could you please navigate to Plesk > Profile & Presence. Make sure that administrator e-mail address is specified in Email Address field and press Apply.

Which e-mail address should be entered there I would have the question what is the difference between adopting and applying

So I have to change the data in my profile? E.g. in Adrian this only administrator?

@Sebahat.hadzhi

 

[Sebahat.hadzhi]

The value you enter there should be an administrator email. The same will be used as an alias for the notification that are sent to "root@localhost," and that should potentially solve the issue you reported.

 

[sauerleander]

@Sebahat.hadzhi

Hello Plesk community,





I’m encountering a DMARC rejection problem when sending emails from my Plesk server through an external SMTP relay (e.g., Mailbox.org).





Here’s the setup:

• Outgoing mail is authenticated via an external SMTP provider.
• The envelope from/SMTP MAIL FROM and the visible From header don’t match because the mail is sent by the SMTP relay but the visible header shows a different domain.
• SPF check passes for the SMTP relay.
• DKIM is not signing the messages.
• DMARC is set to strict alignment (envelope + header) with p=reject.
• The result is that the remote server rejects the mail with a DMARC fail, and bounces are sent back to the visible From address.

I want to:

1. Stop my personal or primary mail address from appearing as the visible From address when sending via the external SMTP provider.
2. Ensure that outgoing mail passes DMARC checks with strict alignment.
3. Avoid bounces being returned to my personal address.

So my core questions are:

• What is the recommended way to configure Plesk so that the From header matches the sending domain for DMARC (without exposing private personal mail in system emails)?
• How should I configure the Return‑Path/Envelope‑From so that bounces go to a neutral mail identity?
• Any best practices in Plesk for handling DMARC when using an SMTP relay that isn’t the same domain as the header From?

Thanks for insights!

 

[sauerleander]

@Sebahat.hadzhi

I sent you a private message with the email header.

 

[Sebahat.hadzhi]

Hi, @sauerleander . Could you please confirm whether we are talking about system emails (notifications), or custom emails that you/users are sending? If the latter, how are the emails sent e.g. via PHP script, webmail, etc.? Thanks in advance.

 

[sauerleander]

Hi, @sauerleander . Could you please confirm whether we are talking about system emails (notifications), or custom emails that you/users are sending? If the latter, how are the emails sent e.g. via PHP script, webmail, etc.? Thanks in advance

These are system notifications

@Sebahat.hadzhi

 

[Sebahat.hadzhi]

Thank you for the confirmation. At this point, it is only possible to change the 'From' field for Plesk email notifications only if Postfix/Qmail is installed on the server. The ability to change it when using MSMTP is yet to be implemented. That is also very likely the root cause of the DMARC failure in your scenario, however, it might be worth the shot to consult with our support staff if you can provide them with direct server access.