help with POP3 syncing between multiple macs

I have recently been put into a position of director of retail operations for a small (<200 employees) retail operation. I basically handle everything other than employee/customer management. Anyway, most of my business correspondence is primarily handled through email, whether it be from my retail management staff, creative services, advertising, distributors, logistics, warehouse management, other supply chain members, etc... and I am having a problem with POP email. Unfortunately I do not have access to IMAP with my company and am forced into POP. Anyway, the new position requires a significant amount of travel. I currently have an iMac in my office, a MacBook Pro for travel, and an iMac in my home office. I've recently raised the concern about having to use my personal laptop for business travel, so my boss has agreed to purchase a MacBook Air for me.

Anyway, I work from my home iMac one day a week, in my office 3 days a week, and a satellite location another day a week. In any given week I could send multiple email messages from my work iMac, home office iMac, iPhone, and MacBook Pro... plus now this MacBook Air, depending on my location. Anyway, I have my POP server set to leave messages on the server, so I can download the messages to each individual device, but when I send a message from my iPhone for example, it doesn't show up on any of my other machines like an IMAP account would. What I would like a solution for is a way to keep both my inbox and sent messages synced. I'm open to any suggestions so please help me swim in this pool of email that I'm currently drowning in. Also, I have no problem checking email on each individual device (IE re-reading messages I've already checked) but keeping the sent messages the same on each device for reference is what I'm primarily concerned about.