Mailgun vs SendGrid for Transactional Email: Which to Choose?

Mailgun and SendGrid have been the two default transactional email APIs for over a decade. Both send receipts, password resets and notifications at scale, both offer SMTP relay and a REST API, and both are now owned by larger telecom companies (Sinch and Twilio). The practical differences are free tiers, inbound handling, log retention and how they treat small senders.

Quick answer

Mailgun is the developer's choice for API ergonomics, inbound routing and EU data residency. SendGrid has the larger marketing toolset and deeper Twilio integration, but it ended its free tier and has become less friendly to low-volume senders. Neither gives you an inbox. If your volume is small and you also need real mailboxes, OquMail bundles a send API with free mailboxes on the same domain.

Feature comparison

• Mailboxes: neither provides inboxes; both are sending platforms with optional inbound parsing
• Free plan: Mailgun offers a small free tier with a daily cap; SendGrid ended its free plan and now starts on a paid tier after a trial
• API: both have full REST APIs, official SDKs and SMTP relay; Mailgun's API is simpler, SendGrid's v3 API is broader
• DNS guidance: both require SPF and DKIM records on a sending domain and recommend DMARC; both show verification status
• IMAP/SMTP: SMTP submission only for sending; no IMAP because there is no mailbox
• Storage: log retention is limited by plan on both; long-term storage of sent mail is your responsibility

Where Mailgun wins

• Inbound routes that parse incoming mail and POST it to your app
• EU region for data residency
• Cleaner API and documentation for a small engineering team
• Free tier still exists for very low volume and testing

Where SendGrid wins

• Marketing Campaigns product alongside transactional sending
• Event Webhook and analytics are mature
• Deep Twilio integration for teams already sending SMS
• Large, well-documented ecosystem of plugins and integrations

Total cost at 5 and 15 users

Transactional providers charge by message volume, not by user, so team size does not change the bill. What changes cost is monthly volume, dedicated IPs and log retention. For a small app sending a few thousand messages a month, Mailgun's free tier or entry plan is cheaper; SendGrid's minimum paid plan is now the entry point. Remember that both still leave you paying a separate provider for the human mailboxes.

The free third option: OquMail

OquMail is not a Mailgun or SendGrid replacement at high volume. It is the right choice when a small business needs receipts and notifications from its app plus inboxes for the team, on one domain, without two vendors. The send API takes from, to, subject and html with a Bearer key, and the delivery log shows the receiving server's response for each message.

• Free plan: up to 15 mailboxes, 3 domains, 5 GB per mailbox, no credit card
• Webmail included; IMAP/SMTP for Outlook, Apple Mail, Thunderbird and phones
• IMAP mail.oqumail.com port 993 (SSL/TLS); SMTP mail.oqumail.com port 587 (STARTTLS)
• Guided SPF, DKIM and DMARC with live DNS verification; MX is mail.oqumail.com priority 10
• Transactional send API at https://api.oqumail.com/api/v1/emails with Bearer API keys (from, to, subject, html)
• Per-message delivery logs so you can see the exact response a receiving server gave

Verdict by scenario

• Developer-led startup that needs inbound parsing and EU residency: Mailgun
• Company already on Twilio or running marketing campaigns: SendGrid
• High-volume sender needing dedicated IPs and warm-up tooling: either, based on pricing
• Small business with modest volume that also needs mailboxes: OquMail

Common questions

Does SendGrid still have a free plan?

No. SendGrid retired its free tier; new accounts get a trial and then move to a paid plan. Mailgun keeps a small free tier with a daily limit.

Can I use Mailgun or SendGrid for my team inbox?

No. They send mail and can parse incoming mail into your app, but there is no mailbox, webmail or IMAP. You still need an email host for people.

Which has better deliverability?

Both deliver well when your domain is authenticated and your list is clean. On shared IPs your neighbours matter more than the brand. Set up SPF, DKIM and DMARC first regardless of vendor.