Content Search in the Security & Compliance Center - Searchable Email Properties

[soctest_1src]

I am attempting to use an email messages message-id to be a unique identifier when running a search via powershell within the Security and Compliance center.  According to the searchable email properties MS link below a message-id is not able to be used but I wanted to make sure this was accurate.

https://docs.microsoft.com/en-us/office365/securitycompliance/keyword-queries-and-search-conditions#...

Any help/confirmation is appreciated.

[#2]

That's correct. The message id is stamped as a header, and we cannot run searches against headers. What we can do is an ID search, but the ID used there is different one: https://docs.microsoft.com/en-us/office365/securitycompliance/csv-file-for-an-id-list-content-search