2 Jan 23, 2019 22:00
Looks like there's a few different logs in the database, including email log. If you're familiar with phpMyAdmin, you could do it there. If you're not familiar with it, you could break your db/site. Do NOT use "Drop". That deletes the actual tables not just what's in them. I think Empty is safe as is deleting the actual contents in groups of 20/25 or whatever shows at one time by using Check All(as in checkboxes) and then Delete Selected. You can also change how many rows show at one time but if you do 200 or something, it might freeze up on you.
Disclaimer: I'm not a programmer or database admin.
The above link plus another source tell me Empty is pretty safe in most cases, especially for temporary data like logs.