Can't send mail ISPconfig 3

September 13, 2014 12.5k views

Hello again!

I’ve a problem with sending mails by squirrelmail (ispconfig3 server).

I can recieve mails but i cannot send and no idea where is the error.

The configuration is the following:

1 domain added to DNS panel and with digitalocean nameservers, same domain added on ISPconfig as domain, mailbox, etc…

Thanks for reading.

1 Answer

Hi again vps and thanks for your time, i did telnet to that server thow port 25 as you told me and i think the problem is there:

Trying (my ip)…
Conected to mydomail.tld
Escape character os ’]^’.
220 server.mydomain.tld ESMPT postfix (Debian/GNU).

  • I am unclear on what you you got back when you telnet to google smtp port.

    Did you get the connection denied or timeout? If so either DO is blocking your outbound port 25. (Think I did see a post about this in ipv6) In that case you will need to open trouble ticket to DO to remove port 25 block. Or google has blocked your ip. Could be previous owner was spammer. You can check some of the common email blacklist at Just enter the ip of your droplet.

    You telnet to your server is as it should be.

  • Hello again, i used the tool to check and mi IP is not listed in any balck list.

    But with this commnad:

    I get –>

    Trying 2404:6800:4008:c00::1b…
    telnet: Unable to connect to remote host: Network is unreachable

  • I am going to guess you created your droplet with ipv6 support.

    Seems be default DO is indeed blocking outbound 25 or ipv6 server setups. See This should be may public when creating a IPv6 droplet.

    If you don’t need ipv6 support just recreate the droplet with only ipv4. I am not sure if you can just create a snapshot and bring it back up as ipv4 or not. This may require another question. Sorry I can’t help you with that.

  • I’ve installed fail2ban and iptables but i cant find the iptable.rules file in /etc/

  • You helped me a lot with finding the problem, thanks for that.

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