I don’t know if this is just a coincidence. I know best practice is to unsubscribe instead of delete known bad emails. However a few days ago i just got so frustrated at the 90K plus emails clogging up shopify and omnisend (our version of klaviyo). Even though we had been mainly successfully quarantining them with rules based segments (no orders, less than 5 page visits including checkout). I went ahead and DELETE this segment. Then 100 more per hour. Then delete again after another day and 2000+ bad emails. Repeat repeat repeat. Last time i mass deleted was about 3 hours ago and i only have 28 new bot emails. So maybe actively deleting does something to the sender to slow it down? I’m sure i deleted a handful of legit customers (at least subscribers, not customers since anyone who has made a purchase is not in the bot segment).
Will post again if i truly see a big slowdown that endures.