Technician replies are not getting sent to requestors

SDP Support is forcing me to use this platform for support rather than try helping me resolve the issue. I'm still evaluating the software, and I'm already having a hard time to get real support.

Anyway, hopping someone can help me with this.

I finally resolved the issue with mail fetching. SDP can connect to the mailbox just fine. No issue with fetching or sending initial emails (ticket assignment, acknowledgement email).

Now SDP is not sending replies to the requestors.

-External user sent email to SDP mailbox.

-Ticket created.

-System generated notification sent to external user email. (we know smtp outbound settings work fine)

-Ticket is assigned to technician.

-Technician replied to ticket with Outlook client, subject line remains intact.

-Requestor did not receive the reply.

Issue happens with both external and internal requestors/email addresses.

Help? Thanks.