Hi all, First I want to take the chance to thank Falko, till and all the moderators/members here for the great help they are providing in this forum for free. Now for my old/new question about ISP blocking port 25. The situation is that I am able to send/receive emails from/to my mail server running postfix with dovecot. The problem is when someone register in my website www-data won't be able to send confirmation emails to the new users getting something like this: postfix/smtp: connect to x-eu.mail.am0.yahoodns.net[18.104.22.168]:25: Connection timed out postfix/smtp: 1FB0B334108D: to=<[email protected]>, relay=none, delay=6930, delays=6900/0.03/30/0, dsn=4.4.1, status=deferred (connect to mx-eu.mail.am0.yahoodns.net[22.214.171.124]:25: Connection timed out) Any idea what can make it refuse connecting other than my ISP blocking port 25 ? As I said before sending emails from webmail.mydomain.com using squirrelmail client have no issue at all.