Pricing.
Mailgun's free plan is 100 emails a day with one inbound route. Basic is $15 a month for 10,000 emails, Foundation $35 for 50,000 with 5,000 validations included, and Scale $90 for 100,000. Notix Free is 5,000 emails a month and 200 a day with no card and no end date; Pro is $15 for 50,000 emails, with usage past that metered on the same invoice at the rate on the pricing page. At 10,000 emails the two cost the same; at 50,000 the gap is $20 a month.
Sending API.
Mailgun's messages endpoint takes form-encoded or JSON fields and supports batch sending with per-recipient variables, scheduled delivery and tags for analytics. Notix takes a JSON body with an idempotency key so a retry cannot double-deliver, and has batch and scheduled sends on the same endpoint family; its email API also covers contacts, templates and campaigns under one key. Both expose an SMTP relay on every plan. A plain transactional send moves between them after a client swap.
Deliverability tooling.
Mailgun sells address validation as a product, from $1.80 per 1,000 on Basic to 5,000 included on Foundation, and offers dedicated IP pools on Scale. Notix has a deliverability check you call before a send, which returns a score and the findings that would block delivery, and a suppression list shared across transactional and marketing mail. The transactional email API page describes both. They solve different problems: Mailgun cleans lists; Notix checks messages. Both verify domains with SPF, DKIM and DMARC and report bounces and complaints.
Marketing features.
Mailgun's sending product is transactional-first; an email template builder arrives on Foundation, and its parent Sinch sells marketing tooling separately. Notix has contact books with double opt-in, a template editor, campaigns and journeys in the same account as transactional sending, on one suppression list, so an address that bounced a campaign never receives a receipt. If you want one vendor for both kinds of mail, Notix bundles it and Mailgun does not.