I recently used Special:MassMessage to send a notification to 1,800+ talk pages. Rather than have the posts signed as "MediaWiki message delivery," I opted to have it signed under my own name by doing the usual [[User:Harej|Harej]]. I ended up getting two notifications about "MediaWiki message delivery" pinging me, even though they were just my own comments. But I only got two notifications, not over 1,800. Both of the notifications were from posts to Flow boards:
In the long term, the way MassMessage messages are attributed should be revisited (T71954: Add support to MassMessage to allow using the sender's username for deliveries), but in the meantime, it shouldn't ping me over my own message.