Add Unitpost to Email

Requirements:
- [x] This is Software as a Service, not self-hosted
- [x] It has a free tier, not just a free trial
- [x] Pricing information is clearly visible without signup or phone calls
- [x] The submission mentions what is free
- [x] The submission is not already present in the list
- [x] The service has contact details of those running it and a privacy policy
- [ ] Large Language Models and other AI tick this box

README.md

@@ -875,7 +875,7 @@ This list results from Pull Requests, reviews, ideas, and work done by 1600+ peo
 **[⬆️ Back to Top](#table-of-contents)**
 
 ## Email
-
+  * [Unitpost](https://www.unitpost.com/) - AI-First Transactional & Marketing Email Service. Free tier: 5,000 emails/mo, 200 emails/day, 10,000 contacts, 5 domains. No credit card required. SDKs, MCP and REST API available.
   * [10minutemail](https://10minutemail.com) - Free, temporary email for testing.
   * [AhaSend](https://ahasend.com) - Transactional email service, free for 1000 emails per month, with unlimited domains, team members, webhooks and message routes in the free plan.
   * [AnonAddy](https://anonaddy.com) - Open-source anonymous email forwarding, create unlimited email aliases for free