When you use Office365 as your Mail Server the messages will come into JIRA and you can setup JIRA to create issues automatically per Creating issues and comments from email. In light of this you may not need to create the connection from O365 to JIRA since JIRA can handle this for you and you can tell your add-on to use the mail server JIRA uses.
In addition, take a look a look at the following Community post:
Hopefully this helps.
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