Email Glossary

Soft Bounce

A soft bounce is a temporary delivery failure. The receiving server accepted the connection but returned the email because the recipient's mailbox is full, the server is temporarily unavailable, or the message exceeds size limits. Most email platforms retry soft bounces for 24-72 hours before classifying them as hard bounces.

Common Causes

  • ●Mailbox full - Recipient's storage quota exceeded
  • ●Server unavailable - Receiving mail server is down or overloaded
  • ●Message too large - Email exceeds the receiving server's size limit
  • ●Content rejected - Temporary content-based rejection (greylisting)
  • ●Rate limited - Receiving server throttling your sending IP

Related Terms

Hard Bounce

A permanent email delivery failure caused by invalid addresses, closed accounts, or non-existent domains.

Bounce Rate

The percentage of sent emails that couldn't be delivered to the recipient.

Delivery Rate

The percentage of sent emails that were accepted by the receiving mail server (not bounced).

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