# What does "550 permit denied" mean in a returned e-mail? **URL:** \ **Category:** Factual Questions\ **Created:** [October 19, 2005, 5:47pm UTC](https://boards.straightdope.com/t/what-does-550-permit-denied-mean-in-a-returned-e-mail/326950 "2005-10-19T17:47:50Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Mr.Blue\_Sky](https://avatars.discourse-cdn.com/v4/letter/m/d26b3c/32.png) [@Mr.Blue\_Sky](https://boards.straightdope.com/u/Mr.Blue_Sky)\ **Post date:** [October 19, 2005, 5:47pm UTC](https://boards.straightdope.com/t/what-does-550-permit-denied-mean-in-a-returned-e-mail/326950/1 "2005-10-19T17:47:50Z")
A co-worker (whose home PC has been seriously infected with assorted trojans and viruses) started getting this message when sending emails to certain email addresses. I Googled it, but didn’t get much info other than it might be trojan/virus related. What’s the dope? ---
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [October 19, 2005, 5:56pm UTC](https://boards.straightdope.com/t/what-does-550-permit-denied-mean-in-a-returned-e-mail/326950/2 "2005-10-19T17:56:12Z")
> [@Mr. Blue Sky](#): > > A co-worker (whose home PC has been seriously infected with assorted trojans and viruses) started getting this message when sending emails to certain email addresses. Try Googling SMTP 550. SMTP is the Simple Mail Transfer Protocol [Here’s](http://www.chilkatsoft.com/faq/Smtp550.html) the first result. [Here](http://www.faqs.org/rfcs/rfc821.html) is the RFC for SMTP. > [@RFC 821](#): > > ``` > Example Undeliverable Mail Notification Message > > S: MAIL FROM:<> > R: 250 ok > S: RCPT TO:<@HOSTX.ARPA:JOE@HOSTW.ARPA> > R: 250 ok > S: DATA > R: 354 send the mail data, end with . > S: Date: 23 Oct 81 11:22:33 > S: From: SMTP@HOSTY.ARPA > S: To: JOE@HOSTW.ARPA > S: Subject: Mail System Problem > S: > S: Sorry JOE, your message to SAM@HOSTZ.ARPA lost. > S: HOSTZ.ARPA said this: > S: "550 No Such User" > S: . > R: 250 ok > > ``` ---
**Author:** ![MyNameIsEarl](https://avatars.discourse-cdn.com/v4/letter/m/e36b37/32.png) [@MyNameIsEarl](https://boards.straightdope.com/u/MyNameIsEarl)\ **Post date:** [October 19, 2005, 7:21pm UTC](https://boards.straightdope.com/t/what-does-550-permit-denied-mean-in-a-returned-e-mail/326950/3 "2005-10-19T19:21:13Z")
Wow - that was helpful, **Quartz** - first you link him to the wrong error message (he’s getting “permit denied” errors, not “unable to relay” errors) and then you link him to the RFC, which is always easy for newbies to read), and then you give him an example of “user unknown” - which is also NOT his problem! The problem is that SMTP error 550 is somewhat generic, meaning only that the “requested action was not taken”. This can happen for any number of reasons. In this particular case, I can’t say for sure what the problem is without seeing the headers from the returned email, but “permit denied” indicates that the user’s IP or user account has been blacklisted by either the outbound email server or the recipient’s POP server. If he can send _some_ emails, then the latter would seem to be the problem. Again, without additional data, a definitive answer is not possible at this time. It might serve your friend better to call his ISP’s tech support line, as this “cuts out a middleman”, so to speak. ---
**Author:** ![The\_Davil](https://avatars.discourse-cdn.com/v4/letter/t/cab0a1/32.png) [@The\_Davil](https://boards.straightdope.com/u/The_Davil)\ **Post date:** [October 19, 2005, 7:39pm UTC](https://boards.straightdope.com/t/what-does-550-permit-denied-mean-in-a-returned-e-mail/326950/4 "2005-10-19T19:39:59Z")
> [@MyNameIsEarl](#): > > I can’t say for sure what the problem is without seeing the headers from the returned email, but “permit denied” indicates that the user’s IP or user account has been blacklisted… And to tag on to this - if I had to guess, I’d say that when your friends machine was jacked by the virii and/or spyware/worm/etc., his/her email addy was hijacked and used to send out spam or other annoying email. This would cause some POP server admins to institute the abovementioned blacklisting on your co-worker in order to avoid any more spam coming from him/her. Again - just a guess… It’d be a cast iron b!tch to clean up, but the first step should be (as mentioned above) for your co-worker to contact their customer service. Hope this helps, David