Email marketing is an essential tool for businesses to reach their audience, but not all emails successfully land in the recipient’s inbox. Sometimes, emails "bounce," meaning they cannot be delivered to the intended recipient. Bounces are categorized into two types: hard bounce and soft bounce. Understanding the difference between these two is crucial for maintaining a healthy email list and improving deliverability rates.
A hard bounce occurs when an email is permanently undeliverable. This means that there is a permanent issue preventing the email from reaching the recipient. Hard bounces usually happen due to the following reasons:
Invalid Email Address: The email address doesn’t exist or has been entered incorrectly.
Domain Issues: The recipient’s domain is invalid or doesn’t exist.
Blocked Email Address: The recipient’s server has completely blocked emails from your domain or IP.
Since hard bounces indicate a permanent failure, these email addresses should be removed from your mailing list immediately to avoid damaging your sender reputation.
Remove hard-bounced email addresses from your list to prevent repeated failed attempts.
A soft bounce occurs when an email is temporarily undeliverable due to a temporary issue. Unlike hard bounces, soft bounces might be delivered successfully in future attempts. Some common reasons for soft bounces include:
Mailbox Full: The recipient’s inbox has reached its storage limit.
Server Issues: The recipient’s email server is down or experiencing technical difficulties.
Email Size Too Large: The email contains large attachments or exceeds the recipient’s server size limit.
Spam Filters: The recipient’s spam filter may be temporarily blocking the email.
Since soft bounces indicate temporary failures, you can attempt to resend the email before removing the address from your list.
Retry sending the email after a short period.
Monitor repeated soft bounces—if an address continues to bounce over time, consider removing it.
Optimize your email size to ensure it complies with server limitations.
Factor | Hard Bounce | Soft Bounce |
Definition | Permanent email delivery failure | Temporary email delivery failure |
Causes | Invalid address, domain issues, blocked email | Mailbox full, server issues, email too large |
Recoverable? | No (Permanent) | Yes (Temporary) |
Impact | Damages sender reputation | May affect deliverability if persistent |
Handling | Remove from mailing list immediately | Retry sending, monitor for repeated failures |
Managing both hard and soft bounces is essential for maintaining a good sender reputation and ensuring high deliverability rates. Internet Service Providers (ISPs) monitor bounce rates, and a high bounce rate can result in your emails being flagged as spam or even blacklisted.
To reduce bounces and improve email deliverability:
✅ Maintain a clean email list by regularly verifying email addresses.
✅ Monitor bounce reports and take necessary action.
✅ Use a professional email service provider (ESP) with proper authentication settings (DKIM, DMARC).
✅ Encourage double opt-ins to ensure valid email entries.