Bounces, Unsubscribes, and Spam Complaints

Bounce

When an email can't be delivered to its recipient, it's considered a bounce. Bounces fall into two primary categories:

• Soft bounces: the system automatically retries these temporary delivery issues, such as an out-of-office reply.
• Hard bounces: a receiving email server permanently rejects a message because the email address is invalid or unfindable.

Rising bounce rates are frequently caused by using stale data or purchased lists that contain invalid addresses and spam traps. Keeping hard-bounced addresses in your database can damage your sender reputation quickly. To prevent this, keep your data clean and maintain a bounce rate under 2%.

To maintain a good reputation, process and remove hard bounces from your lists at least once a week.

To accurately troubleshoot the exact reasons for individual bounces, you can find error code documentation for platforms like Gmail, Microsoft, ProtonMail, and Yahoo!.

Unsubscribes

An unsubscribe or opt-out is an action a recipient takes to stop receiving certain messages. Unsubscribes are processed at three levels.

• Global or Tenant Level: This level is the most restrictive. It blocks all commercial communications across an entire business unit or tenant. When a person unsubscribes here, they are marked as unsubscribed across the entire business unit or tenant, blocking all commercial communication regardless of the brand or topic.
• Topic or Preference Level: This level is organizes consent based on the type of content you share via email, such as newsletters, event invitations, or weekly digests. Someone can unsubscribe from certain categories while remaining subscribed to others.
• Channel Level: This level considers the receiving device. A person can choose to receive only one type of message, such as SMS or email, or some combination of them.

To maintain compliance and trust, include a clear, functioning unsubscribe mechanism in every email. On the preference page, explicitly communicate what the options are and then process requests within 2 to 10 days.

Each Salesforce Marketing app product handles subscription state, data models, and consent headers differently, so review the specific implementation documentation for your product.

Spam Complaints

Spam complaints occur when recipients mark an email as spam, and are the primary factor in determining your sender reputation. If you receive even one complaint per 1,000 emails (0.1%), your reputation can be damaged or result in blocked emails or IP addresses.

Although these complaints define traditional unsolicited bulk email, poor practices frequently trigger them for legitimate senders. Common causes include sending emails too frequently, delaying initial contact until a user forgets their opt-in, or delivering irrelevant content.

To address and prevent these complaints, prioritize strict explicit consent and relevant communication.

Further Reading

To find detailed information and instructions about optimizing email for each marketing app, review this table.