Our company has a lot of people that travel, using laptops when they are on the road.
I have everyone in the company using Thunderbird as their email client. Before they leave for a trip they copy their Thunderbird profile folder, containing all their email, to the laptop. When they return they copy the profile folder from the laptop back to their PC.
I have a batch file with the copy command to do the actual work, they just click on a desktop icon to copy the files to the other system. Of course you will need an email client like Thunderbird, that runs on all platforms, to do that so both systems can use the same files.
I used a simpler method at first. Just set the laptop email client so it doesn't delete messages from the server when it downloads mail. When they are on the road the laptop will receive all their mail, but leaves it in place. When they get back, and check mail with their PC, it will grab all the email received since they left, since it is still on the server. The only problem with this method is that messages 'Sent' from the laptop will only be on the laptop. So when sending mail on the road they would BCC a copy to themselves, and their PC would then have a copy when they get back and check mail.
This doesn't require them to copy/sync their files, but results in some duplication on the laptop when they send mail. Since they copy themselves, all mail sent from the laptop is also received by the laptop when it checks mail. So I went to the second method which takes more setup, but eliminates the duplication on the laptop (one copy in sent folder, another in the Inbox).
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