Definition
Delay send refers to intentionally holding an email from immediate delivery for a set period. This can be a scheduled send at a future date and time, a time-delayed automation trigger, or a brief hold period that allows for last-minute campaign corrections.
More sophisticated delay send applications include send-time optimisation (STO), where the delay is calculated per recipient based on historical engagement patterns, and multi-wave sending, where a campaign is released in waves to test performance before full deployment. Even a short delay — 5–15 minutes — provides a safety window to catch and fix errors before widespread delivery.
Delay Send Use Cases
| Use Case | Typical Delay | Purpose |
|---|---|---|
| Scheduled campaigns | Hours to weeks | Send at optimal time |
| Send-time optimisation | Per-subscriber | Deliver when each subscriber is most likely to open |
| Safety hold | 5–30 minutes | Catch errors before full deployment |
| Multi-wave testing | 1–24 hours | Test and optimise before full send |
| Timezone-aware sending | Calculated per TZ | Ensure emails arrive during business hours |
| Drip sequence timing | Days to weeks | Space automated emails appropriately |
Best Practices
- Use send-time optimisation (STO) for broadcast campaigns to reach each subscriber at their best time
- Build a 5–15 minute safety delay into all automated campaigns
- Schedule transactional emails for immediate delivery — delay only applies to marketing
- Test your delay mechanism to ensure scheduled sends execute as expected
- Monitor timezone data to avoid sending at inappropriate hours
- Document your scheduled send process including timezone handling
Related Glossary Terms
Email Scheduling
Email scheduling is the practice of setting a specific future date and time for an email campaign to be sent, ensuring optimal delivery timing without manual intervention.
Send Time Testing
Send time testing is the practice of systematically testing different email send days and times to identify when individual subscribers or segments are most likely to open and engage.
Timezone-Based Email Sending
Local time delivery for email campaigns using subscriber timezone detection via IP geolocation, browser timezone, and profile data. Send window optimisation and typical engagement lift of 5-15%.
Recency Bias in Email Marketing
Recency bias is the tendency to overweight recent information over historical data, used in email marketing to time campaigns for maximum impact on subscriber decision-making.
Frequently Asked Questions
No, the delay itself does not impact deliverability. However, the time you choose to send does — sending when subscribers are more likely to engage improves open rates and sender reputation. The delay is simply a tool to ensure your email arrives at the best possible time.
Most ESPs allow you to cancel or edit scheduled sends up to the moment of delivery. Some even allow cancellation within the safety hold window. Check your ESP's specific features — this capability varies significantly across platforms.