Onion Mail is described as 'Free encrypted email with Tor .onion support, automatic PGP for all messages, no phone or KYC needed, anonymous payments, and strict no-logs policy' and is a webmail provider in the security & privacy category. There are more than 25 alternatives to Onion Mail, not only websites but also apps for a variety of platforms, including Android, iPhone, iPad and Android Tablet apps. The best Onion Mail alternative is Proton Mail, which is both free and Open Source. Other great sites and apps similar to Onion Mail are Tuta Mail, Disroot, Zoho Mail and Outlook.com.
Onion Mail alternatives are mainly WebMail Providers, but if you're looking for
Email Clients or Calendar Apps you can filter on that. You can also filter by region, for example
EU-based alternatives if you prefer software developed in the European Union. These are just examples - use the filter bar below to find more specific alternatives to Onion Mail.