I have a customer who is experiencing some email delays. Although this happen randomly, they want to fix this issue. Our spam gateway provider [Symantec] advised this is because our internal exchange server configuration that does not accept too many connection at same time
aaaaaa Log for recipient: firstname.lastname@example.org
Received by Ecelerity Msg Id: 46/05-03199-A898C555
Date: Wed May 20 13:20 xxxxxx
Msg Size: 3691129
Source IP: 18.104.22.168
Delivery attempt failure - transient
Attempted delivery 46/05-03199-A898C555 to x.x.x.x on Thu May 21 14:53:40 2015
Error Message: "451 4.4.2 [internal] connection closed by remote host"
Retries attempt: 8
Time message queued: 92137.40seconds
Incoming email comes from internet go to our MX records manages by our spam gateway at Message Labs, then goes to our external firewall, from the external firewall goes to F5 GTM, then flow to Edge servers in a DMZ, and from there finally goes to CAS/MBX servers.
Exchange 2013 SP1 all servers
After looking at the edge configuration [Default receive connector], I can see following values:
Should I increase the value of Max Inbound connections and max inbound connections per source to a higher value?
What should be the right value for a company with the following email statistics?
What is the impact of increasing those values? Is this going to fix my issue?
Should I restart any windows service or the edge servers?
Any performance risk after changing this settings?
See below emails statistics
2900 /24 /60
42000 messages received per day
1750 messages per hour
29.2 messages per min