I have been searching the internet for comparisons of open source e-mail server solutions. After reviewing a lot of blog and vendor sites, I came to the conclusion that I should install and configure Zimbra Collaboration Server (Open Source Edition) to replace Horde. I looked at G-mail and it is my alternative because of the cost to pay for additional storage space above 5gb and you have to pay for the service if more than 5 end-users will be using it. Both products support SSL so we can transmit messages securely and one Zimbra will operate on a Linux/Unix virtual host running on Hype V platform. Another difference is that Zimbra will be controlled by me and not by a third party and I can define my own mailbox size.
My rankings are:
1st Choice: Zimbre
2nd Choice: Gmail (if budget allows)
3rd Choice: Roundcube
Please tell me what you think about my choices and if you have a better suggestion, please share.
Thanks in advance.