On Jun 1, 2015, at 12:39 PM, Aryeh Friedman <aryeh.friedman at gmail.com> wrote: > from any other machine: > telnet mailserver 25 > connection refused Absent other information, I'd imagine your ISP is filtering port 25. Run "tcpdump port 25" on mailserver and retry the remote telnet to confirm. Regards, -- -Chuck