We are using offfice 365 SMTP relay to send mails to the external users through the CRM application, i,e option 3 on the following URL
, this CRM system is allowed only to talk with <domain>.mail.protection.o
on port 25 and 587 and rest of the access to the internet is blocked, not access for this CRM system to http/https to the external network.
1. we observed the CRM system workflow triggers the emails to the external network users only when the port 80 is opened for the CRM system at the gateway/firewall level, we noticed the CRM system gets connected to internet and connects to crl.globalsign.com and from here it is connecting to office365 smtp and emails are delivered.
2. when we disable access to external network i,e port 80 http blocked for CRM system at gateway/firewall then emails does not flow no packets flow found hence no mails are sent.
3. When only allowed CRM system can talk to crl.globalsign.com then emails are getting triggered.
can you please help me understand how this office365 is working when it is configured to the CRM system. is it essential that CRM system to be allowed to talk to crl.globalsign.com . please suggest.