Bulk email, or mass mailing, is the sending of the same or similar message to a large list in one campaign. Newsletters, promotions and announcements are typical examples.
Why it matters
Receivers apply extra scrutiny to bulk senders. Major mailbox providers expect authentication with SPF, DKIM and DMARC, a working List-Unsubscribe header, low complaint rates and valid reverse DNS. Thresholds for what counts as bulk differ and change, so check each provider's current sender guidelines. Sending through a dedicated email service provider is usually more reliable than a web server's built-in mail function, because those providers manage IP pools and feedback loops.
Example
A newsletter to 50,000 subscribers is split into batches of 5,000 sent over a few hours to avoid triggering rate limits. The mail uses a dedicated subdomain, news.example.com, with its own DKIM key, and each message has an unsubscribe link. Complaint rate stays below the provider's guidance, which is often described as well under 0.3%.
Common mistakes
- Sending from a web server's default mail function without authentication.
- Not warming up a new sending IP; see IP warm-up.
- Ignoring unsubscribe and complaint data after each campaign.
Related
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This page is general information written by our editorial team and updated when documentation changes. Servers and providers differ, so test changes safely first. See our editorial policy and disclaimer.