ISPConfig 3 -- unable to receive emails

Discussion in 'Installation/Configuration' started by msun, Feb 6, 2020.

  1. msun

    msun New Member

    Been churning away at this for over 7 hours. Numerous config changes/testing, service statuses/restarts, server rebuilds/restarts. I've been through every forum thread I can find.
    • Fresh VPS server pre-configured by GoDaddy. Ubuntu 16.04 w/ ISPConfig 3
    • I'm 99.9% sure my MX record is set up properly: A[mail]->serverIP, MX[@]->
    • Prep:
      • Brand new server build
      • ISPConfig ServerConfig to add the GoDaddy SMTP Relay to the Relayhost setting, so that I can send outbound mail.
      • ISPConfig EmailDomains to add as a mail domain.
      • ISPConfig EmailMailboxes to add [email protected] as an email inbox.
      • Sidenote: for whatever reason, at this point, I can't send emails until I restart the server. Not sure if this is a GoDaddy/ISPConfig bug or what. Anyway, it seems to be a non-issue after restarting, and I'm able to send outbound emails from [email protected] to [email protected]
    My problem is that no matter what I do, I can't get inbound mail to deliver. I can't get mail to deliver from [email protected] to [email protected], from [email protected] to [email protected], or from [email protected] to [email protected]
    • Normally I'd expect to receive a "Mail Delivery Failure" response in Gmail after sending a failed/undeliverable email. That doesn't happen. Everything seems to indicate the message was delivered, except that it never shows up in the mailbox.
    • I see no errors or warnings in mail.log while sending these messages.
    • Most obviously, I see no status in mail.log that indicates the server is receiving/handling the inbound delivery at all.
    How can I go about troubleshooting this? Any help is appreciated. Thanks in advance.
  2. Th0m

    Th0m ISPConfig Developer Staff Member ISPConfig Developer

    Why are you using Ubuntu 16.04? It's EOL is next year... Better upgrade to 18.04.
    Your DNS settings should be (when using ISPC):
    mail A IP MX mail
    You can verify your DNS settings with a service like or and test your mailserver with the MXToolBox domain tool, and come back with the results to the forum.

    Did you open port 25, 587, and 993 on your server (TCP)?
  3. msun

    msun New Member

    Ubuntu 16.04 was the only option GoDaddy provided. I'll note that I should look into upgrading, thanks.

    Results from MXToolbox:
    0 107.180.*5.*51, LLC (AS26496) 30 min

    I'm not totally sure if I'm opening the ports correctly. For example I use:
    iptables -I INPUT -p tcp -m tcp --dport 25 -j ACCEPT
    iptables -I INPUT -p tcp -m tcp --dport 587 -j ACCEPT
    iptables -I INPUT -p tcp -m tcp --dport 993 -j ACCEPT

    Testing each port from my home using telnet, I'm only able to connect to port 993: i.e., telnet 993
    Port 587 shows "Connection refused."
    Port 25 hangs, probably because my home ISP is blocking it.

    Testing each port while connected to the server via SSH:
    telnet 25: Connection refused.
    telnet localhost 25: Successful.
    telnet 107.180.*5.*51 25: Connection refused.

    Sidenote: A few days ago, I was able to setup a catch-all email forward using Ubuntu 16.04 without ISPConfig installed. i.e., There was a time where the server was successfully receiving email and forwarding it back out to Gmail. I've since rebuilt the server from scratch, using ISPConfig this time.
  4. Th0m

    Th0m ISPConfig Developer Staff Member ISPConfig Developer

    Port 25 is needed for email traffic for sending servers that don't support encrypted connections, so keep that in mind. If you go to ISPC -> Monitor -> Select your server -> Show services, is IMAP-server showing as online?
  5. msun

    msun New Member

    IMAP-Server is Online, along with SMTP-Server and POP3-Server.
  6. Th0m

    Th0m ISPConfig Developer Staff Member ISPConfig Developer

    Did you follow the Perfect Server guide?
  7. msun

    msun New Member

    Nope. Right now I'm trying to stick with what comes pre-configured on the server. Ubuntu + ISPC + all the supporting packages/services.
    I suppose I can rebuild without pre-configured ISPC, and try following Perfect Server Guide.
  8. till

    till Super Moderator Staff Member ISPConfig Developer

    Th0m likes this.
  9. msun

    msun New Member

    I started over using CentOS 7.6. (Unfortunately this seems to be the most future-proof image provided by GoDaddy at the time, as the Ubuntu and Debian images will reach EOL soon.)

    I followed the Perfect Server Guide for CentOS 7.6. Things went pretty smoothly, although there were a few hiccups which still linger.

    Fortunately, now both incoming and outgoing email work as expected. However there are still some issues which I'm concerned about, but I'll request help in a separate thread if necessary.

    Thanks for your help guys!
    Th0m likes this.

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