Transactional Email APIs · reliability comparison
MailerSend vs SparkPost (Bird): which is more reliable? (2026)
MailerSend is more reliable than SparkPost (Bird), scoring 100.0 vs 87.7 out of 100. Over the last 90 days MailerSend reported 0 incidents and SparkPost (Bird) reported 8, with effective uptime of 100% and 99.90% respectively.
Data updated Nov 2, 2026 · How we score
| Metric | MailerSend | SparkPost (Bird) |
|---|---|---|
| Reliability score | 100.0 | 87.7 |
| Rank (transactional email APIs) | — | #6 |
| Uptime (90 days) | 100% | 99.90% |
| Incidents (90 days) | 0 | 8 |
| Partial / major outages | 0 | 0 |
| Avg time to resolve | — | 2h |
| Outages we detected | 0 | 0 |
| Transparency score | 100/100 | 100/100 |
Where MailerSend and SparkPost (Bird) differ
- MailerSend reported no incidents in the last 90 days, while SparkPost (Bird) reported 8.
90-day uptime
MailerSend
SparkPost (Bird)
- No incidents
- Degraded
- Partial outage
- Major outage
- No data
Recent MailerSend incidents
- MaintenanceSep 23, 2026 · ongoing
Affected: Email sending API, Email analytics, Deliverability rate, MailerSend APP, Bulk endpoint, SMTP +2 more
- MaintenanceSep 15, 2026 · ongoing
Scheduled maintenance - Email sending affected, 5 min
Affected: Bulk endpoint, SMTP, Delivery time, Email sending API, Inbound routing
Recent SparkPost (Bird) incidents
- InformationalOct 30, 2026 · resolved in 22h 2m
Outbound message delivery is delayed/slow for some SparkPost customers (US hosted only)
Affected: SMTP Delivery - USA
- Degraded performanceOct 28, 2026 · resolved in 1h 1m
Outbound message delivery is delayed/slow for some SparkPost customers (US hosted only)
Affected: SMTP Delivery - USA
- Degraded performanceOct 11, 2026 · resolved in 3h 6m
Increased message delays in US and EU due to DNS resolution errors
Affected: SMTP Delivery - USA, SMTP Delivery - EUROPE
- Degraded performanceOct 1, 2026 · resolved in 31m
Affected: SMTP Delivery - USA, SMTP Delivery - EUROPE
- Degraded performanceSep 17, 2026 · resolved in 54m
Outbound message delivery is delayed/slow for some SparkPost customers (US hosted only)
Affected: SMTP Delivery - USA
- Degraded performanceSep 14, 2026 · resolved in 2h 27m
Health Score and Cohort data is delayed
Affected: SparkPost Application - USA, SparkPost Application - EUROPE
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 →