Your email can bounce for a variety of reasons:
- Unknown User. The part of the email address before the @ is incorrect or expired)
- Over Quota. The recipient's mailbox is full.
- Domain Error. The part of the email address after the @ is incorrect.
- Spam. Your message was considered spam.
- Too Large. Your message was too big (most likely images or attachments).
Of the above reasons, "Unknown User" and "Domain Error" are considered "hard bounces"—this means the email address is no longer valid and should be removed from your list.
The other bounces are considered "soft", because the address may begin to work again at some point in the future. For example, the recipient might clear out his or her mailbox and thus free up some room in their quota. You can safely leave these recipients your list and Direct Mail will try them again the next time you send.