Dear Team,
We are trying EASendMail trail version which we will purchase soon.
When using EASendMail in web application to send email in local host everything works fine.
We deployed this web application to web server. and consumed it from postman, it is working.
However when consumed from another web application we get below error.

System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host

What could be the root cause?

from web server we are able consume SMTP with port 443
https://outlook.office365.com/EWS/Exchange.asmx 

We are using Exchange server to send email.

Regards,
Ravi.