[Mimedefang] Sendmail delivery Problems

[Christoph]

My Problem seems to be Sendmail related, but perhaps somebody can give me a 
hint.
Situation :
We use Sendmail and Mimedefang to relay Mails to our Domino Server.
Everything was fine for weeks until the Domino-Server crashed.
I thought that all mails are queued until the Domino Server is back on line , 
but i waited 15 minutes and Sendmail still cant deliver Messages to Domino :
"....Deferred: Connection refused by lotus1.company.com....."
>From the Linux - Server i made a telnet on Port 25 to the Domino Server and 
everything was fine, i was able to send messsages.
I restarted sendmail, but  the messages still could not be delivered.
I restarted the Linux Server and after that all Messages could be delivered.
This Situation is reproducable when i shutdown the Domino Server !

Did anyone know why messages could not be delivered, or how i can send
messages again without rebooting the Linux Server ?
Is this a configuration Problem in Sendmail ?


Thanks for help

Christoph