I am on the verge of making a big leap towards regular use of GNU/Linux. For that to happen, I need to settle down on a good email client. I require some opinions from expereinced users. Under Windows, I have been using Outlook Express 6. I have many email accounts spreaded across multiple identities. If possible, I would like to continue enjoying this facility. Please keep this in mind when expressing your opinion. Please help me decide which is the best email client under this great OS. Not only cast your vote, but also give reasons. Thanks.