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Deliverability Letter

Acceptable Use Policy

Also known as: AUP

An Acceptable Use Policy (AUP) is a set of rules defined by an ESP or ISP that governs what type of content and behavior is allowed on their network.

Every Email Service Provider (ESP) has an Acceptable Use Policy (AUP). It outlines prohibited activities, such as sending spam, purchasing lists, or promoting illegal goods.

If you violate the AUP—for example, by receiving too many spam complaints or sending to a scraped list—the provider has the right to suspend your account or block your IP. When you see a bounce error mentioning "AUP violation" or "Policy blocked," it means you have crossed a line defined in that provider's terms of service.

Compliance with the AUP is essential for maintaining your account standing and ensuring your emails get delivered.