[pseudalopex]

Bulk senders give up in hours.[1][2] Some will even unsubscribe you.[3]

[1] https://postmarkapp.com/migration-guides/mailgun#processing-...

[2] https://forums.aws.amazon.com/thread.jspa?threadID=145330

[3] https://mailchimp.com/help/soft-vs-hard-bounces/