Mailgun vs SendGrid: Run One Identical Sending Test

Mailgun and SendGrid solve the same problem and price it differently enough that the published comparison rarely settles the question. Mailgun reaches 30 days of log retention at $90 per month; SendGrid reaches 7 days at $89.95 and sells longer history separately. For a program whose replies arrive across two weeks, that single difference outweighs every line item on either homepage, and a demo will not surface it. Run both against one identical send and let the returned data pick the winner.

Set the published plans side by side

The figures below come from the Mailgun pricing page and the SendGrid Email API pricing page, both checked on September 19, 2026.

The two pricing models differ in an important structural way. Mailgun publishes the included volume and the overage rate for each tier, so the cost at any send level can be calculated from the page. SendGrid determines price by volume band and by which capabilities you select, so the published $19.95 and $89.95 are floors at the smallest band and the real figure comes from the volume selector or a quote.

Our view: Mailgun is easier to budget from public information. SendGrid gives more room to negotiate at scale. That difference matters most to whoever has to defend the number in a finance review, which is a procurement consideration rather than a technical one.

Decide the retention question first

Log retention is where the two products genuinely diverge, and it is the criterion that should be settled before anything else.

SendGrid's pricing page lists searchable email activity at 3 days on the free trial and Essentials, and 7 days on Pro and Premier, with additional email activity history available for purchase. It also notes that the extended option is not available to Premier customers at 100M volume and above. Mailgun publishes 1 day on Free and Basic, 5 days on Foundation and 30 days on Scale.

For an outbound program the reply cycle routinely exceeds a week. A prospect responding on day nine referencing a message you cannot retrieve is an ordinary occurrence, and the ability to produce the exact message sent is what separates a professional answer from an apology.

At the roughly $90 mark, Mailgun gives 30 days inside the platform and SendGrid gives 7 with a purchasable extension. If retention is the binding constraint and you intend to rely on the vendor console for it, Mailgun wins that row outright.

Run one identical send before deciding

Neither vendor's documentation will tell you how its platform handles your list, because neither has seen it. The evaluation has to generate that data itself.

Set up both platforms with the same authenticated sending domain configuration, split one real list evenly by a method that does not correlate with domain or seniority, send the same content at the same time, and record the results against a fixed set of measures.

1. Confirm SPF, DKIM and DMARC alignment on each platform before any message leaves, and document the exact records used.
2. Split the list randomly and hold the split allocation so the comparison can be rerun.
3. Send identical content from both platforms in the same sending window.
4. Record accepted counts, delivered counts, bounce classifications, complaint events, event webhook latency and the time to first support response on a real question.
5. Compare cost per delivered message rather than cost per message sent.

That last measure is the one to put in front of a budget holder. A platform with a lower published rate and a higher bounce rate can cost more per delivered message than the more expensive option, and only the identical send exposes it.

Compare the operating controls that matter under pressure

Once the delivery data is in, the remaining differences are about what happens when something goes wrong.

Start with bounce classification detail. A platform that reports a generic failure code leaves you unable to distinguish a dead mailbox from a temporary block, and those two conditions require opposite responses, so the depth of the classification sets how much of your list hygiene can be automated.

Complaint feedback coverage decides whether you see the metric that triggers an account review before the vendor acts on it. Confirm during the test that complaint events actually arrive for the receiving domains that dominate your list, since coverage varies by receiver.

Then measure event webhook latency, because suppression enforcement and reply routing both depend on it. Both platforms offer webhooks; the test is delivery guarantee under your volume, not whether the capability exists. SendGrid publishes webhook counts by plan at 2 on Essentials and 5 on Pro and Premier.

Last, price suppression ownership, which sets the cost of the next migration. Confirm on both platforms that the suppression list exports in a usable format before you commit, because that export is what you will need if this comparison runs again in two years.

Check the traffic type on both before you pick either

Transactional infrastructure providers apply acceptable-use terms to the kind of mail they accept, and the terms are not identical. The most expensive outcome in this comparison is choosing correctly on capability and then having the account reviewed because the traffic was never a fit.

Put the description in writing to both vendors during the evaluation. Name the list source, the recipient relationship, the monthly volume and the expected complaint rate, then keep both written answers with the decision record. If one vendor answers with a specific position and the other sends a link to a policy page, you have learned which account will be easier to defend later.

Our SMTP relay service guide for cold email works through the selection test for outbound traffic specifically, which is the case neither vendor's documentation is written to address.

Pick the one your evidence supports

Mailgun and SendGrid are close enough on core delivery that the decision should come from your own data rather than from either pricing page. Mailgun gives longer retention and a more calculable cost at the comparable tier. SendGrid gives a broader feature surface, more validation on Premier and more negotiating room at volume.

Settle the retention question, run the identical send, compare cost per delivered message, and keep the written traffic-type answers from both. LeadHaste orchestrates 35+ tools for client programs and picks the sending layer against the traffic and the team that has to operate it.

LeadHaste can design and run the controlled comparison, then turn the result into a quote-ready operating model with the retention and reputation plan attached. Book your free ICP and campaign-fit discovery call →