A particular external Customer's email always fails to create a new ticket through Email request

[tyamaguchi]

Hi, 

A different user from <https://community.atlassian.com/t5/Jira-Service-Management/An-email-from-an-external-Customer-did-not-create-a-JIRA-ticket/qaq-p/2200671?utm_source=atlcomm&utm_medium=email&utm_campaign=mentions_reply&utm_content=topic>

but a constantly experienced issue.

Whenever one of our existing Customer contacts emails my support team to <support@myCompany.jp> set in the Email Request, his email fails to create a JIRA ticket. We work around this problem by manually creating a ticket for them, then use gmail (so not Customer Reply from JIRA) to avoid any chance of losing emails in future communication. This happened once back in March/April, and now occurs again on Nov 29.

Log shows the original email was not received by <support@myCompany.jp>.

How should we troubleshoot?

Is it possible for Atlassian to look into whether the customer's email address is stuck or having any issue on your end? (therefore unsupress it)