Email

MS Live Hotmail

Google Mail

Yahoo Mail

GMX

web.de

De-Mail

ePOST

eMail / Calendar

Microsoft

• MS Office: Outlook
• Windows Mail

Lotus Notes

• LotusLive

mozilla Thunderbird

• Seamonkey
• Calendar Project 

Apple Mail

Evolution 
Zimbra
Eudora
Pegasus
Incredimail
The Bat (RiTLabs)
Incredimail

Web Clients

Opera

Messenger & Chat

MS Live Messenger

• Web Messenger
• Office Communicator 

Yahoo Messenger

Google Talk

AIM

Skype

Empathy  |  Pidgin
Trillian  |  meebo
KOOL IM  |  Miranda
ooVoo  |  fringg
GMX MM
eBuddy

ICQ  |  mIRC  |  IRC+  |  tinychat

Jabber

Collaboration