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A soft bounce is a temporary email delivery failure that occurs when an email cannot be delivered due to a temporary issue, such as a full mailbox, server downtime, or message size limits. Soft bounces may succeed on retry.
Recipient's mailbox is full
Email server is temporarily unavailable
Message is too large for the recipient
Recipient's server is experiencing high load
Temporary DNS issues or network problems
While soft bounces are less severe than hard bounces, repeated soft bounces indicate underlying issues. A mailbox that's consistently full may be abandoned. A server that's always down may no longer exist. Ignoring soft bounces can lead to list decay and eventual hard bounces.
Allow your ESP to retry delivery automatically (usually 3 attempts)
Track consecutive soft bounces for each address
Convert to hard bounce after 3-5 consecutive soft bounces
Remove addresses that soft bounce on every campaign
Investigate sudden spikes in soft bounce rates
Not immediately. Give soft bounces a chance to resolve. If an address soft bounces 3-5 times consecutively across multiple campaigns, treat it as a hard bounce and remove it.
Sudden soft bounce spikes often indicate recipient server issues, temporary blacklisting, or problems with your sending infrastructure. Check if the bounces are concentrated on one domain and investigate accordingly.
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