[actsasbuffoon]

Everyone who sends email has to be very careful about upsetting email service providers, because they'll mark your messages as spam if they suspect you of misbehavior. Email providers use many metrics, and one of them is the number of bounced emails.

It doesn't take much to be marked as a bad actor, so companies will quickly remove you from their lists if you're jeopardizing their ability to get into the inboxes of their other users.

Source: I've worked at a couple of companies that used email as a significant part of their strategy to keep in touch with users.

[gt565k]

Very true. I've used SendGrid and Mandrill for transactional email services and bounces count against your account's reputation.

Most of them will require warming up the account/IP you're sending the emails from in order to increase the quota of emails you can send per hour/day.