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.
Where sender reputation sits on Postmark
Postmark has no mailbox to warm. It relays the mail your app hands it, and it is built for transactional mail rather than cold outreach. Reputation sits on your sending domain and the IP, and mailbox providers build it from what recipients do with your mail.
Seed lists for Postmark senders
You pay for Postmark, the list and the campaign whether anyone reads the mail or not. When Gmail files it in spam, it goes unread, and Postmark still counts it as delivered.
MailStrike seed lists put real Gmail and Outlook inboxes on your recipient list. You add the seed addresses to your Postmark send, and each seed inbox:
- opens the email and stays on it
- moves it out of spam or promotions into the inbox
- marks some of it important
Gmail and Outlook read that engagement when they decide where the rest of your mail goes. You also see where the real send landed in Gmail and Outlook: inbox, promotions or spam.
Use them two ways:
- Mixed into a send. The seeds go out with a real campaign and engage with it as it arrives, so the send carries good signals while it goes out.
- Sent to first. The campaign goes to the seeds before your list, so the content and the domain have engagement on record when the real send goes out.
Setup is a CSV of seed addresses you add to your recipient list like any other contacts, and one DNS TXT record. It works the same day, and seed lists are sold on their own.
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
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%.
How do seed lists work with Postmark?
You add MailStrike's seed addresses to your Postmark send. Real Gmail and Outlook inboxes open the email, move it out of spam or promotions and mark some of it important, and Gmail and Outlook read that engagement when they place the rest of your mail. Setup is a CSV of seed addresses on your recipient list and one DNS TXT record.