There are two main protocol for accessing your emails via client. IMAP and POP3. The following are the main differences
IMAP coordinates with the server, POP3 does not coordinates with the server
Email synched via IMAP are shown read if they are read on the server, Email obtained through POP3 are marked as unread even though they are read on the server
Email sent via IMAP is stored on the server, Email sent via POP3 is NOT stored on the server
You can access all your sent email from Web client, You can only see those message through web client that you sent through web client
In my needs, I want to be able to access all my emails both on my local machine as well as from web on the go so I definitely prefer IMAP + the extra advantage that my message are automatically marked read once I read it on the sever.
Those people who don’t want to leave a copy on the server for security reasons, POP3 is a good option. For them someone has to get hold of their PC to check their emails. This is usually not required unless you are working in an organization or law firm where someone can be made accountable based on their emails. Generally IMAP is the way to go for work environment as snyc all you data on the server. No worries about not finding your email.
So for me IMAP is the way to go!