Why is mail not getting triggered from Splunk System?

[velayudhan]

Hi Team

   Facing issue in the Mail Trigger . 

   SMTP Connections are valid but mail is not triggered and receiving the following error

command="sendemail", [WinError 10060] A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond while sending mail

Splunk Version : 9.0.4

Kindly support on this 

[richgalloway]

Splunk is unable to connect to your SMTP server.  The message implies a firewall is dropping connection attempts to the SMTP server from Splunk.