Email throttling is the practice of controlling the rate at which emails are sent to internet service providers (ISPs) and recipients to avoid triggering spam filters or exceeding sending limits. It is a common technique used in email marketing and transactional email systems to maintain deliverability.
Email throttling involves slowing down the delivery of emails rather than sending them all at once.
ISPs often monitor email traffic and impose limits on how many messages can be accepted from a single IP address or domain within a specific timeframe. Sending too many emails too quickly can result in temporary blocking, throttling by ISPs, or emails landing in spam.
By managing the sending rate, email service providers (ESPs) and marketers ensure a steady flow of emails that comply with ISP guidelines and maintain sender reputation.
The process of email throttling typically includes:
Some advanced systems use adaptive throttling, adjusting rates based on ISP response and recipient engagement signals.
Email throttling is critical because it:
Without throttling, aggressive email sending can harm sender reputation and significantly reduce deliverability.
Email throttling is widely used for:
Example scenario: An e-commerce company launches a holiday sale campaign to 500,000 subscribers. Instead of sending all emails instantly, the ESP throttles delivery in small batches over several hours to maximize deliverability.
No. Scheduling determines when emails are sent, while throttling controls the rate of sending within a given period.
Yes. Most reputable ESPs implement throttling automatically to optimize deliverability.
Yes. Large lists may take hours or even days to complete sending, so plan campaigns accordingly.
