In-Reply-To header is parsed incorrectly by JIRA sometimes. Override JIRA and parse the header correctly.
2016-06-03 18:43:27,529 Caesium-1-3 ERROR anonymous Bewerbungen [c.a.jira.mail.MailThreadManagerImpl] Unable to parse incoming In-Reply-To header JIRA.130028.1456993126000@Atlassian.JIRA
This issue has been released as of version 7.0.19
We are seeing this error just recently in our logs. We find that when a customer replies to an email (sent from JIRA Service Desk), the response is not inserted back into the call as a comment. This used to work but has just stopped working for us. We are seeing errors:
Unable to parse incoming In-Reply-To header <JIRA.XXXXX.XXXXX@XXXXX>
Mail Message appears to be in Mail Handler Log, processing skips it now.
We are using JETI 7.0.23-jira6