How To Configure Receive Email From The Internet/Outside

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After installing Zimbra as described at this guidance : installing Zimbra on CentOS 6 or install Zimbra on CentOS 7, by default we could sent email to outside/internet if have the internet connection and port 25 outgoing is not blocked by firewall or blocked by ISP connection. After that, usually try to receive email from internet/outside and never coming to Zimbra that has been installed. This problem occurs because some information below :

1. We should have the real domain that known on the internet. You can bought a domain from Godaddy or other provider

2. We should have at least one Public IP. You can rent a VPS from Digital Ocean or other provider and then install Zimbra in it

3. We should have dns management for configure A and MX Records. If you also bought hosting on your domain provider, usually you can manage dns on cPanel or something else. If you bought a domain only, you could using Free DNS management from Hurricane up to 50 domain and configure your domain nameserver to refer to Nameserver of Hurricane.

In this section, i have a domain that has been bought from Godaddy and have 1 Public IP and dns management on cPanel (Hosting from Excellent Infotama Kreasindo Inc). This is what i do for a configuration to receive emails from internet/outside

# Configure A Records on DNS Management (cPanel)

Select Advanced DNS Zone Editor and add A records (see the following picture)


After adding A records, please check for dns propagation at this link : whether name (you can using another name) has been known in the internet or still propagate

# Configure MX Records on DNS Management (cPanel)

After configure A Records on cPanel, go to home and select MX Entry. If you have been saw existing MX records using 0 (zero) priority, change it to 50 or 20 (or you can remove it if not needed). Add MX records to refer to the name who has been configured formerly and give 10 priority.


After adding MX records, please check for dns propagation at this link : whether the new MX records for domain has been known in the internet or still propagate.

After above configuration has been configured, you should be able to receive emails from internet/outside.

Good luck and hopefully useful 😀


  1. Hi Iman,

    Thank you for your note.. Really a nice one…. I followed the procedures of installation and in my domain i am receiving the mails from other domain but i am not able to send mails to other domains. I have valid MX and PTR. Kindly need your help on this…

    1. Hello Manikumar,

      For sending email to outside, you should :
      1. Use static IP
      2. Open port 25 outgoing
      3. Nothing firewall for port 25 outgoing

      For testing port 25 out, please paste the result from the following command

      telnet 25
  2. Hi Iman,
    In my network i am having 2 ISP’s. As of now i configured everything in network 1 and i would like to do whenever the network 1 is goes down network 2 should live. Please help me on this.

  3. HI iman,
    I install zimbra 8.6 on centos 7. My mail was sending /receiving even on outside network (internet) but i cant send to other domain without smtp relay.. do I really need to have it? How can I send to other domain using my own MTA(without relay)? Thanks..

    1. Hi,
      By default, you can direct sending email into outside without relay. But, if your public IP was blacklisted anywhere, you should use smtp relay

  4. Hi sir Iman,

    I have a problem to send email outside sir everytime i send a email to other domain i receive undelivered mail returned to sender. but i try to send email to and yahoo this is already receive my email..

    here is the error sir iman.

    : host[] said: 550 5.7.1
    Service unavailable, Client host [] blocked using Spamhaus.
    To request removal from this list see
    (AS16012611) (in reply to RCPT TO command)

    Thank you sir iman.

      1. Hi Sir Iman,

        Thank you sir Iman,

        How can i protect my public ip to this spamhaus.

        please help me sir,

        Thank you

  5. Hi Iman,
    In my network i am having 2 ISP’s. As of now i configured everything in network 1 and i would like to do whenever the network 1 is goes down network 2 should live. Please help me on this.

  6. hi sir iman,
    i have problem. I followed the procedures of installation.
    sending mail to other success, but can’t receive from other mail server.

    I Use static Public IP, Open port 25, Nothing firewall for port 25. Mx Record and PTR record, public IP not blocked.

    Please help me on this.

  7. Hi sir Iman,

    how can I protect my public ip so it wont be in the blacklisted?
    Our public IP was blacklisted so i cant send and recieve to other domain ex:

    Please help me on this sir. thank you

  8. Sending email from gmail or yahoo -> my zimbra mail server, resulted to 554 5.7.1 Relay Access denied

    What to configure on my zimbra server ?

    1. Hello,
      Please ensure all services running well. And ensure your ip has been listed on trusted network (Zimbra Admin | Configure | Servers | Edit | MTA | Trusted Network)

  9. HI Sir Iman,
    I am running Mail zimbra 8.8.15 with 30 domain.
    Main domain:
    29 Other domain have been running normal.
    Now I want add more one domain :
    I created domain : Home > Configure > Domain.
    After that, I add dns: @ mx and cname: mail Cname
    Sent email outgoing. IT was ok
    Sent email incomoing: error
    Send from zoho mail
    “This message was created automatically by mail delivery software.
    A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. INVALID_ADDRESS”
    Send from Gmail
    “Message not delivered
    Your message couldn’t be delivered to because the remote server is misconfigured. See technical details below for more information.
    The response from the remote server was:
    550 relay not permitted”

      1. i check with my laptop to telnet using my ip server in the same network connection and than connected (like: telnet 25), but i trying using telnet with my domain but could not open connected to the host. This is problem with the mx record, but if i check in mxtoolbox ( the result is DNS Record Published, but if i trying smtp test in that mxtoolbox Unable to connect after 15 seconds.

        1. *There is problem with the mx record?

          and one more thing 😀
          if i open Mail Queues in admin control zimbra that was some error like this :

          Server error encountered
          Message: system failure: exception executing command: zmqstat all with {RemoteManager:>zimbra@domain:22} Error code: service.FAILURE Method: [unknown] Details:soap:Receiver

          does this have to do with problems receiving emails?

        2. Hi,
          It means port 25 incoming is closed. Please ask to ISP to open the port 25 incoming. Port 25 incoming is mandatory to open if want to receive email from outside

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