Apps similar to MailOdyssey include Forward Email, which is open source with a free version. Other options are ImprovMX.com and Migadu. In total there are three WebMail Providers like MailOdyssey for the web and self-hosting.
Forward Email is the best email service, encrypted email service, and fastest email service. It supports unlimited domains and aliases for no extra cost. It uses quantum safe ChaCha20-Poly1305 encryption and offers SMTP, IMAP, POP3, email webhooks, email regular expressions...
United States
ImprovMX lets you forward emails from your domain to your personal inbox. You can create aliases to redirect any mailbox and even use webhooks to connect your emails to your app.
Netherlands
EU
Consolidate all your email addresses and domains at a flat price. Take back your email liberty and give unlimited email addresses to all your projects, clients and family members.
Switzerland