can't send email via smtp - sql auxprop plugin using sqlite3 engine

[krawuzikapuzi]

Good day,
i have a new installed virtual server (Suse 11.1+Plesk 9.5.3) and i have migrated domains and so on from a backup (same system). Now I am not able to send emails via smtp (e.g. with Mozilla Thunderbird). I get a connection error: connection to smtp server failed, not available or denied.

In /var/log/messages I can find a lot of entries (about 7-10 every hour) like this:

postfix/smtpd[9782]: sql auxprop plugin using sqlite3 engine

What can i do, to fix the problem?
Best thanks

 

[IgorG]

What sort of errors in /usr/local/psa/var/log/maillog ?

 

[krawuzikapuzi]

can't find there any errors - i tried a few times to send a mail, but actually there is no error in maillog

 

[IgorG]

Did you check that port 25 is accessible?

 

[krawuzikapuzi]

Plesk Panel Firewall shows a green button at SMTP - allowed from every source.
But nmap -p 25 domain.tld put out:
PORT STATE SERVICE
25/tcp filtered smtp

I tried
telnet mail.domain.tld 25
connection failed

how can i open this port in plesk panel for sending mails?