Today all of a sudden since last 3 hours no users could do send & receive mails using mail clients & also web interface was not working, everything was normal on server, we've restarted server & also restarted SM service than almost after 30mins thing went normal

 

Error received on Web interface 

"No connection could be made because the target machine actively refused it 127.0.0.1:17001"

 

Error received while sending mails using mail clients

451 Requested action aborted: error in processing

 

Issue resolved on it's own & that's worrisome as we still don't know root cause of issue

 

using SM 11.x Entp edition 

 

Regards,

Dev