Definition
Batch sending, also known as throttling or wave sending, is the process of dividing a large email send into smaller segments and sending them over a period of time. Instead of delivering one million emails simultaneously, a marketer might send ten batches of one hundred thousand over several hours.
Batch sending helps protect sender reputation by avoiding sudden spikes in volume that can trigger throttling or spam filtering at mailbox providers. It also gives senders the opportunity to monitor early engagement metrics and pause the campaign if problems arise.
This technique is commonly used during high-volume sends such as product launches, holiday promotions and major announcements. When paired with engagement monitoring, batch sending can significantly reduce risk while still reaching the full audience.
Best Practices
- Send the first batch to your most engaged subscribers to establish positive signals.
- Space batches based on mailbox provider limits and your domain's reputation.
- Monitor delivery, open, click and complaint rates after each batch.
- Pause the send if complaint rates spike or delivery rates drop.
- Use batch sending for new domains or during major volume increases.
Related Glossary Terms
Abandoned Cart Email
An abandoned cart email is a triggered message sent to online shoppers who added items to their cart but did not complete the purchase.
Abandoned Cart Email
An abandoned cart email is an automated message sent to customers who added items to their online shopping cart but left without completing the purchase. It is one of the highest-converting email types in ecommerce.
Email API Integration
Email API integration is the connection between an email platform and another system, such as a CRM, ecommerce store or customer data platform, using an application programming interface.
Back-in-Stock Email
A back-in-stock email is a triggered message sent to shoppers who requested notification when an unavailable product becomes available again.
Behavioral Email
Behavioral email is a message triggered by a subscriber's action, inaction, or engagement pattern, making it more relevant than scheduled broadcast sends.
Bounce Classification
Bounce classification uses SMTP codes (550, 551, 552, 553, 554, 450, 451, 452) and enhanced status codes to categorise permanent and transient delivery failures.
Frequently Asked Questions
Batch sending protects reputation, reduces throttling, and lets you catch deliverability issues before the entire list is affected.
It depends on your list size and reputation. Intervals of 30 minutes to several hours are common, especially for high-volume sends.
No. If done correctly, it often improves engagement by sending to the most engaged recipients first and optimising based on early results.
Yes. Warming a new domain with gradual batch sending is a standard deliverability best practice.
Batch sending sends the same message to groups at scheduled intervals. Triggered sending sends individual messages based on subscriber behaviour or events.