Mailgun review (2026): pricing, and why not for cold email

What Mailgun is

Mailgun is an email API and SMTP relay for developers, owned by Sinch and sold under the Sinch Email name alongside Mailjet. Applications use it to send receipts, password resets and notifications, to receive inbound mail through routing rules, and to validate addresses before sending. It belongs in a cold email directory for the same reason SendGrid does: people look at it when deciding how to send outreach, and the answer is that it is built for something else.

How Mailgun’s pricing works

Prices rise with the monthly volume you choose on the pricing page. Free allows 100 emails a day with one custom sending domain and a day of logs. Basic costs $15 a month for 10,000 emails with no daily limit, and extra mail costs $1.80 per 1,000, so Foundation becomes the cheaper plan above about 21,000 emails a month. Foundation costs $35 for 50,000 emails or $75 for 100,000, and adds 1,000 custom sending domains, templates, five days of logs and inbound routing. Scale costs $90 for 100,000 emails and climbs through $215, $400, $550 and $700 to $1,250 for 2.5 million, adding a dedicated IP with automated warmup, 5,000 validations, SAML SSO, phone and chat support and 30 days of logs. Foundation and Scale both start with a free month.

The self-service terms run month to month and renew automatically, ask for 30 days’ written notice of non-renewal, and say nothing about refunds. Mailgun commits to 99.99% availability for its API, SMTP and delivery services, with service credits if it misses.

Why Mailgun is the wrong tool for cold email

Start with the policy, because it is explicit. Mailgun’s acceptable use policy prohibits acquiring or sending to third-party lists, names bought, rented and scraped lists, and allows non-transactional email only to people who gave clear, explicit and provable consent, through a single or double opt-in. You must be able to prove that consent when a complaint escalates, and the terms let Mailgun suspend the service for a breach. A cold list fails every one of those tests.

Then the mechanics. Relays are judged on complaint and bounce rates across everything they send, so they watch yours closely, and a cold campaign pushes both up quickly. On the lower plans you share IP pools with other customers, which is exactly why the policy is strict.

Finally the product. A cold email works when a prospect replies to a person. Mailgun sends from a domain you verify, but there is no mailbox behind it and no Google or Microsoft account lending it reputation; replies need inbound routing and your own handling.

What to use instead

The model that works is real mailboxes at a real provider, warmed up, spread across several domains, connected to a sequencer and held to conservative daily volumes. Every tool in our inbox provider category follows it, and it is what warmed Google Workspace and Microsoft 365 inboxes from PureMail are for. Keep Mailgun for the transactional mail your product sends.

Mailgun alternatives

For transactional email, SendGrid is the closest like-for-like, with a 60-day trial in place of a free plan. Postmark is stricter still about what it will send, and keeps transactional and broadcast mail on separate streams. Mailtrap adds a testing sandbox to its sending API. The SMTP relay category compares them.

Who Mailgun is for

Developers and product teams sending transactional and opted-in email through an API, particularly those who need EU data residency or a dedicated IP at moderate volume. For cold outreach, look elsewhere.