I have a web application in which mail is sent to the user on button click(Agent runs on button click). Mail is being sent to the internal users from both web and client but mail is not being sent to the external internet users like xxx@yyy.com from web. However mail is being sent to external internet users from client. Please assist.
In trouble shooting you need to narrow things down.
What we have here is 2 possible issues the server or the agent. I would suggest you out the agent by point a notes client to that server (change location doc) and sending a email from the client. If that has issues then you have a server configuration issue.
As far as smtp it can route to the other server to send out or can send from that server to your mail relay.