On 31 Jan 2021, at 18:13, Wietse Venema <wie...@porcupine.org> wrote: > > Patrick Proniewski: >> I'm looking for a tool/service that would help me diagnose delivery problems >> to my server? Any hint appreciated.
> What about good old telnet or netcat? because I'm looking for a way to test as many remote locations as possible, or get a complete assessment. Most (probably 99,99%) SMTP clients successfully talk to my MX server. Even if it fails later (anti spam, blacklist, etc.) I get connections from many clients. I'm trying to debug cases when the initial TCP connection is not even seen (firewall logs, tcpdump, etc.). > wzv$ telnet mail.patpro.net smtp > Trying 193.30.227.216... > Connected to mail.patpro.net. > Escape character is '^]'. > 220-Do not say anything yet > > Here is a pointer: > > https://tools.ietf.org/html/rfc2821#section-4.3.1 fixed: $ telnet mail.patpro.net 25 Trying 193.30.227.216... Connected to mail.patpro.net. Escape character is '^]'. 220-rack.patpro.net Do not say anything yet thanks! patpro
