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Alternatives

Postmark alternative for AI agents: AgentiSend compared (2026)

Is AgentiSend a Postmark alternative?

Yes, for transactional email an agent sends through an API. A Free plan that does not expire: 1,000 emails a month, 100 a day, 3 domains, no card. Then plans from $9 a month (Starter, 30,000 emails). No plan daily cap; delivery paced per inbox provider. Or 20% off paid yearly. It is not a replacement for a product that is ahead on the rows marked in the other column.

Pick Postmark when you want 45 days of message history on the $15 plan, inbound mail on Pro, or a dedicated IP with a published price; pick AgentiSend when an agent holds the key and you want a send budget and a kill switch. The figures below are from Postmark pages fetched on 28 September 2026 and from this product's pricing table and published API.

What mattersAgentiSendPostmark
A spending limit per keyEvery key is created with a send budget. The send path refuses with agent_budget_exceeded when it is spent, and a key cannot raise its own. The plan inclusion is a second ceiling (plan_limit_reached).A per-key send budget is not on the pricing page. API permission controls are listed as a feature.
What a refusal tells youEvery refused request carries code, message, fix (the call that repairs it), docs_url and retryable.A fix field naming the next call is not on the idempotency article or the webhooks overview.
A retry never sends twiceIdempotency-Key is accepted on every endpoint that changes something and remembered for 7 days.Postmark does not support an idempotency key. The support article says to detect duplicates yourself.
How long the log keeps a message7 days on Free, 30 on Starter, 90 on Pro, 180 on Scale. It is part of the plan and there is no add-on to buy.45 days of activity on every listed plan. Pro and Platform can buy custom retention from 7 to 365 days.

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