RainLoop 
Official Website
https://www.rainloop.net/Category
WebmailRainLoop is a modern web-based email service that fully supports IMAP and SMTP including SSL and STARTTLS. It is lightweight and offers direct access to the mail server.
RainLoop is a modern web-based email service that fully supports IMAP and SMTP including SSL and STARTTLS. It is lightweight and offers direct access to the mail server.