I am facing an issue while receiving an emails from my remote email server which is hosted in USA to local email server which is located in my LAN. My local email server will fetched emails by POP3/POP3S service after every 5 minutes from USA server by catchall email accounts and then distribute all the emails to local users by local email server.
Receiving emails scenario,
Internet > Email Server (USA) > Firewall > Local Email server > Local users
Sending email scenario,
Local users > Local email server > Firewall > Internet
Note: The USA server is just used for receiving an emails not for sending purpose.
Previously, the above mentioned scenario was done by TMG ISA server now I had replaced with fortigate firewall 100D in Active / Passive mode.
As per our observation and troubleshooting we found that Mdaemon (our local email server ) have a transfer rate is not more than 30 kbps whereas on TMG ISA server it will be reached upto 900 Kbps. This affecting on our emails our all emails are stuck in queues at USA server and we faced delays of many hours to receiving an emails on local server.
Please note that no security profile is enabled on policy. Policy is very simple. I have also configured traffic shaper to assign the BW upto 20 Mbps but it didn't cross the 30 kbps. i have total upstream BW is 30Mbps.