Qmail does not send emails to yahoo (4.4.1)

[stamos]

I have a weird issue with qmail, it seems to send email to all hosts except of yahoo.com/.de/.gr/.fr etc.

the logfile says this:
Oct 20 10:08:41 qmail: 1192867721.798389 delivery 3947: deferral: Sorry,_I_wasn't_able_to_establish_an_SMTP_connection._(#4.4.1)/
Oct 20 10:08:41 qmail: 1192867721.798476 status: local 0/10 remote 19/20
Oct 20 10:08:41 qmail: 1192867721.798618 starting delivery 3949: msg 89026 to remote *****@yahoo.gr

this happens mainly to yahoo receiver but also some other receiver are together.

any ideas?!