Check for Exposure to Russian hacker email accounts?
 

Consider adapting and running this search (which works to search an individual mailbox via the fastmail.com web interface search box) to your service:

Search string for the emails in a table in the USDOJ's Internet Research Agency Indictment -
https://www.justice.gov/file/1035477/download :

in:* ( wemakeweather@gmail.com OR allforusa@yahoo.com OR antwan_8@yahoo.com OR xtimwaltersx@gmail.com OR unitedvetsofamerica@gmail.com OR patriototus@gmail.com OR beautifullelly@gmail.com OR staceyredneck@gmail.com OR ihatecrime1@gmail.com OR staceyredneck@gmail.com OR ihatecrime1@gmail.com OR thetaylorbrooks@aol.com OR wokeaztec@outlook.com)