1

Go to JIRA Administration -> System -> Mail -> Incoming Mail

 
 

Setup the "POP/IMAP Mail Servers" that has to manage incoming mail queue

 
 

Outgoing Mail and SMTP Mail Server

 
 Add a new Mail Handler 
 Add a mail handler name, the related server and choose "Approval Mail Handler" as Handler Type,

Click Next and Save

 

Approvals by emails have been activated