Transactional Email APIs · reliability comparison
Mailchimp Transactional (Mandrill) vs Postmark: which is more reliable? (2026)
Mailchimp Transactional (Mandrill) is more reliable than Postmark, scoring 90.6 vs 68.3 out of 100. Over the last 90 days Mailchimp Transactional (Mandrill) reported 3 incidents and Postmark reported 8, with effective uptime of 99.93% and 99.58% respectively. Mailchimp Transactional (Mandrill) resolves incidents faster on average (3h 4m).
Data updated Nov 1, 2026 · How we score
VS
| Metric | Mailchimp Transactional (Mandrill) | Postmark |
|---|---|---|
| Reliability score | 90.6 | 68.3 |
| Rank (transactional email APIs) | #5 | #10 |
| Uptime (90 days) | 99.93% | 99.58% |
| Incidents (90 days) | 3 | 8 |
| Partial / major outages | 0 | 0 |
| Avg time to resolve | 3h 4m | 7h 41m |
| Outages we detected | 0 | 0 |
| Transparency score | 100/100 | 100/100 |
Where Mailchimp Transactional (Mandrill) and Postmark differ
- Postmark reported 2.7× as many incidents as Mailchimp Transactional (Mandrill) over the last 90 days (8 vs 3).
- Mailchimp Transactional (Mandrill) fixes problems faster: 3h 4m on average, against 7h 41m for Postmark (2.5× quicker).
- Mailchimp Transactional (Mandrill)'s longest incident on record lasted 4h 26m (Sep 15, 2026); Postmark's lasted 1d 3h (Feb 1, 2026).
90-day uptime
Mailchimp Transactional (Mandrill)
Postmark
- No incidents
- Degraded
- Partial outage
- Major outage
- No data
Recent Mailchimp Transactional (Mandrill) incidents
- Degraded performanceSep 17, 2026 · resolved in 38m
Delayed Deliveries via Mandrill
Affected: Delayed Deliveries via Mandrill
- Degraded performanceSep 15, 2026 · resolved in 4h 26m
Delayed Deliveries via Mandrill
Affected: Delayed Deliveries via Mandrill
- Degraded performanceSep 1, 2026 · resolved in 4h 8m
Affected: Mandrill/Transactional Delays
Full Mailchimp Transactional (Mandrill) reliability report →
Recent Postmark incidents
- Degraded performanceOct 27, 2026 · resolved in 1h 43m
- MaintenanceOct 7, 2026 · resolved in 3h
- Degraded performanceSep 28, 2026 · resolved in 2h 6m
- Degraded performanceSep 28, 2026 · resolved in 3h 59m
- Degraded performanceSep 22, 2026 · resolved in 20m
- Degraded performanceSep 17, 2026 · resolved in 1h 33m
Other transactional email APIs to consider
- Mailjet · #1 · 100% uptime
- Mailtrap Email Sending · #2 · 99.99% uptime
- Loops · #3 · 99.98% uptime
- Twilio SendGrid · #4 · 99.98% uptime
See the full most reliable transactional email apis ranking →