Hi there, I trust you are well. I am having an issue with a clients site on ISPConfig 3, whereby SMTP does not resolve the IP for mail.[domain]. The issue appears to be that the server is resolving locally only: # dig mail.[domain] ; <<>> DiG 9.18.24-1-Debian <<>> mail.[domain] ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 45788 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 1232 ; COOKIE: 4b4859ec6619bf20010000006609747503fa113fb11a9c92 (good) ;; QUESTION SECTION: ;mail.[domain]. IN A ;; Query time: 0 msec ;; SERVER: 127.0.0.1#53(127.0.0.1) (UDP) ;; WHEN: Sun Mar 31 16:34:29 SAST 2024 ;; MSG SIZE rcvd: 73 The master DNS server for this domain is external, and I don't have a local set of DNS records set. How do I ensure external resolution on the domain?
Hi Till, I trust you are well. There is a DNS record on the external DNS server, which is resolvable from my local machine: Locally I get: $ dig mail.[domain] +short [ip] On ISPConfig server no record is returned. I activated the DNS zone to see if this helps, and now the IP of the remote mail server is returning from a dig command, but the SMTP settings still are not able to connect. SMTP works fine when using the hostname of the remote server however. Perhaps not related to ISPConfig, but rather to the remote mail server then?
The issue is basically the same as in the other thread you started: DNS resolving seems to fail on your system, which causes various other services to fail. So you must try to fix resolving for external domains and this should then fix all other issues.
Thanks Till. The issue appears to have been caused by two things. The resolution issue as there were no external nameservers assigned to the ISPConfig server, then The SMTP plugin on the clients website rejected the SSL certificate because Plesk (the other server) uses webmail.[domain] rather than the mail.[domain]. Using insecure settings resolved the issue. All is well now. Thanks so much.
