Yes, Colosseum Online Inc. supports IMAP.
Mail Settings:
Mail Server Username: full email address (ie. example@yourdomain.com)
Incoming Mail Server: mail.yourdomain.com
Incoming Mail Server: (SSL) otho.colosseum.com
Outgoing Mail Server: mail.yourdomain.com (server requires authentication) port 25
Outgoing Mail Server: (SSL) otho.colosseum.com (server requires authentication) port 465
Supported Incoming Mail Protocols: POP3, POP3S (SSL/TLS), IMAP, IMAPS (SSL/TLS)
Supported Outgoing Mail Protocols: SMTP, SMTPS (SSL/TLS)