VendorClue research · software cost principles
Free transactional email: monthly quotas and daily caps
A free allowance can fit a test and still fail a busy day.
- Evidence
- Sources linked below
- Source check
- 2026-10-11
- Author
- VendorClue editorial
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At a glance
The short answer
A free transactional plan is fine for testing, but its daily cap decides whether it survives a busy day. Resend Free allows 3,000 emails a month and 100 a day, and Mailjet Free 6,000 a month and 200 a day. Postmark’s free plan allows 100 emails a month and SMTP2GO Free 1,000. Size the plan for your busiest day, not the monthly average.
Calculate the busy day first
Estimate password resets, receipts and notifications during your busiest day. Count recipients rather than API calls: a single request may target several recipients. Leave room for retries and inbound messages if the chosen supplier counts them.
Distinguish daily and monthly limits
Resend Free lists 3,000/month and 100/day. Mailjet Free lists 6,000/month and 200/day. Postmark Free lists 100/month; SMTP2GO Free lists 1,000/month. Do not divide a monthly quota by thirty and treat the result as an enforced daily limit.
A free plan is a trial of your integration
Verify a sending domain, send a test template, trigger a bounce and check how the app handles an unavailable provider. Store the delivery events you need independently when the provider’s event history is too short for your investigation process.
Know the upgrade trigger
Write a threshold for upgrading before the cap is reached. Confirm whether the supplier pauses sending, charges overage or asks for an upgraded subscription. A trial that expires after a fixed number of days should be budgeted differently from an indefinite free tier.
Match support to the risk
For operational email, decide who handles an incident outside office hours. Check actual plan support channels rather than a logo or a general help page. If a missing receipt blocks your business, include the response process in the purchase decision.
Sources
Figures in this guide come from the suppliers’ official pages, checked on 11 October 2026. Confirm the plan you buy at checkout.
Resend: official product and plan documentation · Evidence: documentation · Oct 11, 2026
Postmark: official product and plan documentation · Evidence: documentation · Oct 11, 2026
Mailjet: official product and plan documentation · Evidence: documentation · Oct 11, 2026
SMTP2GO: official product and plan documentation · Evidence: documentation · Oct 11, 2026