UV Outliner
Free
UV Outliner is a single pane outliner with multicolumn support.
Microsoft Exchange Server
Commercial
Microsoft Exchange Server is a mail server and calendaring server.
Zarafa
Commercial
Zarafa is an open-source groupware application.
hMail Server
Open Source
hMailServer is a free open source email server for Microsoft Windows.
MDaemon Messaging Server
Commercial
MDaemon Messaging Server is an e-mail server software for Windows.
Compare iRedMail with alternatives
Compare UV Outliner and iRedMail and decide which is most suitable for you.
Compare hMail Server and iRedMail and decide which is most suitable for you.
Compare Microsoft Exchange Server and iRedMail and decide which is most suitable for you.
Compare MDaemon Messaging Server and iRedMail and decide which is most suitable for you.