Mail.com or GMX Mail
Date of use:2010-2012
I am using GMX from the past 2 years. It's so easy, convenient without any hassles. I use it for all biz communications. It had also integrated with my BlackBerry very conveniently. I would request them to provide a read receipt so it can be completely used as a business communication email client. And the storage and uploading of files is very convenient.