iRedMail/cubemail not sending to certain domains.

Posted December 22, 2020 1.4k views

So, I set up an iRedMail, Postfix SMTP, Dovecot IMAP, Nginx, MariaDB, Amavised-new, SpamAssassin, ClamAV, Roundcube, and iRedAPD Postfix policy server for greylisting (which I removed). All on Ubuntu 18.04 server.

Everything works fine when sending out through roundcube to emails such as gmail, etc – though it detects it as spam, and it receives mail fine as well to gmail.

The main problem is it will not deliver mail to other emails of friends on other domains or receive it ( It returns the following error when sending out from cubemail: host[ip.add.ress] said: 550-Verification
failed for 550-No Such User Here 550 Sender
verify failed (in reply to RCPT TO command)

My friend receives the following error when trying to send me an email to the mailserver:
No Such User Here

Reporting-MTA: dns;
Action: failed
Final-Recipient: rfc822;
Status: 5.0.0 is the email I’m sending from to and it doesn’t go through, and vise versa, even though I know the email exists. It also will not send to forwards he has that point to his account.

/var/log/mail.log displays the same error and is of no help.

Here is how my machine and his machine are configured just for clarity. MX records point to another ip outside of the server its domain is hosted on. There are, however, no mx records on as it doesn’t have domains pointing to it via DNS servers to handle it for hosting sites, etc. is by itself at its webhosting company and has many forwarded aliases to the friend account, which are reached through other emails, just not any from, and he cannot send any to

All I’m trying to do is have my mail for a certain domain whose website is hosted on a different server, to handle its mail on a different server, thus leaving its web address alone, etc. I seem to be missing something that is not allowing other domains to recognize it, yet gmail has no problems.

What could be the problem here? Any help is appreciated.

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2 answers

HI @kelloggChrisp,

Usually, these errors are generated when you have the same domains on one host. host[ip.add.ress] said: 550-Verification
failed for 550-No Such User Here 550 Sender
verify failed (in reply to RCPT TO command)

Basically, if you have the domain on the same droplet/server, mail servers try to send the e-mails locally first. Is that the case here? Do you have any trance of the domain you are trying to send your friend to on the same system?


  • No, they’re not on the same host. I’m not sure what you mean exactly by trance, but even if I try to make an account on the webserver, and then send the mail from the mailserver’s test account to a non-gmail email address it bounces. It actually bounced back from an @mail spare account I have as well saying 500 no such user, but there so obviously is one. When sending out to the test mail that is on the mailserver, from anywhere but gmail, I receive a user doesn’t exist. So, it’s happening both ways, but somehow gmail is getting past it.

    • Hi @kelloggChrisp,

      It was a typo, I wanted to type in trace rather than trance.

      Anyway, let me see if I get this straight. It’s not only your friend’s domain that you are getting issues with. It doesn’t care from where to where you are sending, you are always receiving a bounce-back message with the rare exception of sending over to gmail, is that correct?

      • Oh, I’m sorry, I miss read.

        That’s correct. Except it isn’t just gmail now, seems to work and a few others I have tested, too. Reading over your previous message, I realized I replied unclear. So, here is the problem put differently and summerized, so it’s hopefully easier to understand.

        I have two domains. They are both on a webserver for hosting their websites (apache), including one of the domain’s mail. The other domain (domain2) has its own mailserver that is pointed through from the webserver’s mx record, so it forwards all @domain2 mail there. And it works, however, the first domain cannot send nor can it be sent to from domain2, it gives an error about no user existing (500) from both ends. That means when I send to it from domain2’s mail server it bounces back 500, and when I send out from the webserver, it bounces back. Also, some other domains that have nothing to do with either server cannot receive or send out to the mailserver’s email account @domain2.

        The account I’m trying to send to on the webserver sends and receives mail fine to everyone but @domain2. @domain2 sends and receives mail fine from a handful of servers (this may be a resolve thing).

        So, in your previous post when you stated both domains being on the same host, they are indeed, but not for mail.

        • Hi @kelloggChrisp,

          Thank you for clarifying.

          The problem with the domain2 an domain1 not being able to send e-mails is exactly that they are on the same server even if their MX record is different.

          So, how it works: When you have two domains on the same server - domain1 and domain2. Even if domain2 has a different MX record, when you try to send a message from domain1 to domain2, the server domain1 is sending from, the same domain2 is on but not it’s emails sees that domain2 is actually on the server and doesn’t check the MX record of the domain it just tries to send the message locally however since there is no such e-mail account it bounces.

          For a test, you can try and create a test e-mail account on the webserver where domain1 and 2 are and try to send a test message. I guarantee the message will be received on the same server.

          As to how to fix it. There is a setting called Local delivery. You need to turn it off for domain2. This setting should be in the configuration file of your mail service.


          • That makes sense. Unfortunately, the webhost providing the two domains webserver, doesn’t allow for me to disable local delivery. Do you think it would be wiser to just have their mx records handled on another nameserver (the mail server) and have the A name point to the webserver for the website? That way I don’t have to worry about the local delivery problem. I’m trying to do all I can to move the domain off of the webserver because their email doesn’t use any type of anti-virus before delivery. It’s fine for hosting the website and its account, but its mail is causing issues.

Hi @kelloggChrisp,

Unfortunately, even if you change MX records and Nameservers, the same issue will appear. The only way to fix this is by turning off the local delivery, at least that I know of.