Unable to send and to receive mails (qmail) since today

Dear experts

Since this morning, our qmail reports the following when we try to send a mail:

2008-07-23 13:06:21.203413500 starting delivery 3: msg 261365 to remote wwwrun@www.wsl.ch
2008-07-23 13:06:21.203427500 status: local 0/10 remote 1/20
2008-07-23 13:06:21.206351500 delivery 3: deferral: Sorry,_I_wasn't_able_to_establish_an_SMTP_connection._(#4.4.1)/
2008-07-23 13:06:21.206362500 status: local 0/10 remote 0/20
2008-07-23 13:24:30.381655500 starting delivery 4: msg 202975 to remote info@fedex.net
2008-07-23 13:24:30.381659500 status: local 0/10 remote 1/20
2008-07-23 13:24:30.777815500 delivery 4: deferral: Sorry,_I_wasn't_able_to_establish_an_SMTP_connection._(#4.4.1)/
2008-07-23 13:24:30.777818500 status: local 0/10 remote 0/20

The only change since yesterday:
The virus scanner has updated (like every night). We use mcafee and the system is a SuSE Linux.

The responsible person for this mailserver is not rechable.
Has anyone an idee how to fix this? This is very urgent.

Kind regards
Reto

Update:
The service faded out since yesterday. Yesterday at 6 pm we received the first errors (once every 5 to 10 minutes), then it got worse and since today 10 am we are not able to get or send any mails.Start Free Trial