Email issues

Email issues

My email settings are working, somewhat. My fetch works perfectly and crates tickets on an inbound email. The ticket then emails out the info for the newly created ticket to the requester perfectly. But whenever I go to reply in the ticket or run a report and email it I get Failed: Mail sending Failed. No error number or info that I can use. Anyone know how to correct this? 

Service Desk Plus 

8.2.0 Build 8206

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