What happens when you exceed the limit
Account paused pending review. Sending services enforce their quotas at the API, so the failure is explicit and immediate. The reputation of the domain you send from is a separate matter that the quota does not protect.
How the limit interacts with a warmup ramp
Transactional-first; not for cold outreach. A warmup ramp and a provider cap are two different ceilings. The cap is where Postmark stops you; the ramp is where reputation would stop you first. MailStrike's default ramp climbs to 30 warming emails a day per mailbox over 21 days, and real outreach starts at 20 to 30 a day once the ramp is done. Set the provider, the domain's age and the target volume below to see the schedule.
| Outreach a day, per mailbox | 1 mailbox | 2 mailboxes | 3 or more |
|---|---|---|---|
| Not sending yet | 30 | 21 | 18 |
| 10 emails | 30 | 21 | 18 |
| 20 emails | 25 | 18 | 15 |
| 30 emails | 20 | 14 | 12 |
| 40 emails | 15 | 11 | 9 |
| 50 emails | 10 | 7 | 6 |
The rule behind the table: a mailbox on its own that is not sending yet warms at the plan default of 30 a day, and once outreach starts it drops one warming email for every two you send, down to a floor of 10. Put a second mailbox on the domain and each one needs 70% of that figure, three or more and each needs 60%, because the domain earns the signal across all of them. Volume is a setting per mailbox, so you can dial these in directly.
Trial, free tier and new-account restrictions
new accounts manually approved; 100 test emails until approved. Free and trial tiers exist to test integration, not to run campaigns; the volume above them is a plan decision.
The bulk sender rules are a separate limit
None of the caps above is the line that decides placement. Google's and Yahoo's bulk-sender requirements and Microsoft's 2025 high-volume rules set authentication, spam-rate and unsubscribe conditions that apply well below any sending cap; the sender requirements page has them provider by provider, and the auth checker tests a domain against them.
How Postmark compares
documented cap per day (log scale); basis differs per provider
- Brevo sending limits
- Google Workspace sending limits
- Gmail sending limits
- Microsoft 365 sending limits
- Outlook.com sending limits
- Zoho Mail sending limits
Questions about Postmark sending limits
What is the Postmark sending limit per day?
No fixed daily limit; account paused if spam complaints exceed 0.1% or bounces exceed 10%. Source: Postmark's own documentation, checked 6 Sep 2026 (page dated 2025-10-27).
What happens when you exceed the Postmark sending limit?
Account paused pending review. Above the plan's allowance, sending resumes when the quota or plan allows.
How many recipients per message does Postmark allow?
50.
How do I increase the Postmark sending limit?
new accounts manually approved; 100 test emails until approved. Volume above that is plan-based: No fixed daily limit; account paused if spam complaints exceed 0.1% or bounces exceed 10%.
Does the Postmark limit change how you warm up?
Transactional-first; not for cold outreach.