possible skip error 550 (recipient address rejected)

Discussion in 'Installation/Configuration' started by iceget, Jul 17, 2019.

  1. iceget

    iceget Member

    dear community,
    my primary domain is hosted on microsoft online. now i have installed a ispconfig server in my network for internal mailings.
    on microsoft i have 10 email addresses running (as mailbox).

    now on my local ispconfig server i have there only 3 email addresses.
    i want now send the mails out over the static ip address from my network, but postfix writes always Recipient address rejected: User unknown in virtual mailbox table because i only need 3 emails which are used localy.

    can i bypass this message that postfix dont check on local server if mailboxes exists?

    my purpose:
    we want use for internal communication "free" mailboxes they we dont must buy on microsoft.

    all emails they go to the official email addresses, will be redirected to [email protected], but the outgoing mailboxes are currently my problem.

    can i bypass this?

    thank you very much,

    many greets
  2. Taleman

    Taleman Well-Known Member HowtoForge Supporter

    I am not sure, but you probably can. But why? If there is no mailbox with the recipient address and the receiving mail server accepts the e-mail, what can be done with the e-mail? It must be thrown away or you have to set up a mailbox that receives all these e-mails without valid recipient.
    I find the post very confusing. It is not the sending e-mail server that checks "User unknown in virtual mailbox table", it is the receiving e-mail server that does that. The sender can not know what mailboxes exist in the receiving e-mail server.
    Even more confusing is the part microsoft mail server plays in this. How do the mailboxes in microsoft affect your internal ISPConfig setup?
    What are "the outgoing mailboxes"?
  3. iceget

    iceget Member

    dear taleman,

    thank you.

    i want use multiple email addresses in hybrid that means:
    on microsoft online i have the domain for example testdomain.com. here i have 10 emails:
    [email protected]
    [email protected]
    [email protected]

    All working fine.

    now i want use my local isp config machine, for adding for exmaple [email protected].
    now if i do that, i get back this message. my main goal:

    on microsfot online i will add redirection [email protected] that redirects me this email then to
    [email protected]

    the alias domain local.testdomain.com is added in ispconfig as alias for testdomain.com, that means if any user sends out a mail to [email protected] on microsoft, then the mail will forwarded to my ispconfig email server. the local user get then the emails from microsoft online too.

    but the return way is my problem:
    if i send now from ispconfig a new mail from [email protected] to for example [email protected], then i get the message BUT i only want bypass this message, that the outgoing email route send the mail directly to the mailserver from microsoft online.
    on my local ispconfig server i only have added the needed email addresses, not the other 10 from microsoft online.

    i want use local email addresses in my network for about 100 users. the official microsoft online mailboxes we need there only 10 pieces (what need the full exchange functionality).

    i dont want now license 100 users on microsoft online... i dont need for this 100 users the exchange functionality. there i need only pop3 service. therefor i installed ispconfig for this 100 users.

    Way from microsoft is not the problem. i add a redirection to my local ispconfig server (with a subdomain as alias for the maindomain). but the way from ispconfig to microsoft online is blocking because this error message.

    i hope now you can understand my project.

    thank you very much for your help
  4. Taleman

    Taleman Well-Known Member HowtoForge Supporter

    When the sending e-mail server determines where to send the e-mail, it does not look the part to the left of @ character. The Domain name, that is the part to the right of @ character, is looked up in the name service and the e-mail is sent to the mail server pointed to in the MX record.
    So if you have two mailboxes, [email protected] and [email protected], the sending server sends them both to the same server. So if the receiving server does not have mailbox email11, the result is reject with user unknown.
    Check what the MX record is for your testdomain. What shows this command on the sending e-mail server:
    host testdomain.com
    The MX record is the server shown after "mail is handled by".

    So having @testdomain.com e-mailboxes both on your internal server and microsoft server is complicated, do not do this. You would need MX magic to get it working. Use another mail domain for your internal mail server, something like [email protected]. Then you can make suitable MX record for office.testdomain.com pointing to your internal e-mail server.

    I apologize if you already know all of the above, my advice is based on my best guess of the problem. If I am wrong, try to describe the problem in more detail and leave out the parts that already do work.
  5. iceget

    iceget Member

    okay thank you taleman, i have dropped this idea. i work now directly with a subdomain in front of the normal domain. thank you very much!

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