550 message submission is for authorised users only!

Operating System & Version
CentOS v7.9.2009
cPanel & WHM Version


Jurassic Moderator
Staff member
Oct 19, 2014
cPanel Access Level
Root Administrator
Hey there! Is this a normal email sent from the Webmail interface of a cPanel account, or is this message being sent from a different type of mail tool?

If this is a standard Webmail message, can you check the Exim log at /var/log/exim_mainlog to see if thee are any additional details there?


Well-Known Member
May 28, 2022
Mansfield, Nottingham, UK
cPanel Access Level
Root Administrator
Ok, antispamcloud.com is a domain name operated by N-Able on their Mail Assure product (they also use mtaroutes.com btw).

As @cPRex asked, how is the email being sent out from your server? According to N-Able the "550 message submission is for authorised users only" message should only be generated under the following conditions:
I assume your mail client is sending out from your cPanel server (and you are not trying to send out via a Mail Assure system)?

Can you try a service such as Mail Tester (where you just need to send an email to the email address shown, wait about a minute and then click "check your score") or MXToolbox's Deliverability tester or the comprehensive CheckTLS TestSender tool (or even RedSift's OnDmarc's service - but they may send you marketing emails) to confirm that it isn't a problem with the email address you are sending to.

If it still fails, I'm going out on a limb and guessing that either your email client is configured to send out via N-Able (either deliberately , through an MX/IP address misconfiguration or because there's a forwarder/filter in place somewhere).
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