Yes. None of the Firefox Monitor help pages mentioned receiving multiple emails for the same data breach, or how to turn off emails for a data breach after marking it as resolved. I had received emails for data breaches before but never had gotten more than one per breach. The only option in the preferences of the Firefox browser related to Monitor is the one for [[Firefox Password Manager - Alerts for breached websites|alerts within the password manager]], which are not relevant here since I did not have the account's password stored in the password manager. There are no options to turn off emails on the Monitor website, other than to just drop the affected address off Monitor entirely. The alerts seem to now have stopped after the 48th email, at 13:34 UTC, so I suppose this might have resolved itself now. I asked this question on the Firefox forum because there was no link anywhere to [https://support.mozilla.org/en-US/questions/monitor the Monitor forum]. I only found it by trying out various URLs, and it is completely empty, which sounds like an issue with the support site itself.