The answer is yes and no. Sorry to be so oblique.

Thunderbird natively stores mail in MBOX mail format. This is a fairly common text based database format used of email. But Windows knows nothing of it.

To do what you want you probably want the mail in EML format. Their are many converter program on the web, all I have used appear to work about the same. It is also possible to set up an account in Thunderbird that accesses the MBOX files directly. But it is not as simple as it should be so unless our specifically interested in trying this route I will not mention it further.

Mail in EML format will appear in Windows searches and double clicking the files will open the default mail client (Thunderbird)

The import export tools add-on can export mail directly from Thunderbird in that format, so ou might want to look at exporting your profile before you try and relocate it to a new machine..

https://addons.mozilla.org/thunderbird/addon/importexporttools/

Do these converter programs yield data that is searchable by the same categories and filters that the TB client facilitates?

I.e., would I be able to search within subfolders?

would I be able to search by sender, recipient, date, emails with attachments, starred, etc?

"It is also possible to set up an account in Thunderbird that accesses the MBOX files directly. But it is not as simple as it should be so unless our specifically interested in trying this route I will not mention it further."

Could you tell me more about that? I'm interested in the approach which would most closely allow me to search through the emails in a similar fashion to how TB allows me to.

Is the ImportExport tool better than simply copying and pasting my TB profile from old computer to an external drive, and then copying it and pasting it from the Ext drive to my new computer?

If you want to search messages using Thunderbird and its tools then you need to have them in a profile. You could use a profile switcher or manager to decide which profile to use when Thunderbird starts, and I see no reason why one or more of your profiles couldn't be on a second disk drive. The difficulty with multiple profiles is that its not easy to move information form one to another. So while you could refer to old messages, it would be tricky to make use of the information you glean from them.

The converters and the export tool suggested to you will generally export the messages to some alternative message format, such as HTML or even as separate eml files, but you won't be able to search these from Thunderbird.

Windows Explorer has built-in search tools and there are third party search tools you could use.

Zenos said

The converters and the export tool suggested to you will generally export the messages to some alternative message format, such as HTML or even as separate eml files, but you won't be able to search these from Thunderbird. Windows Explorer has built-in search tools and there are third party search tools you could use.

(1) Is there any particular converter program you recommend?

(2) Please clarify: If I use Windows to search emails converted by one of these programs, will I

(a) be able to search -- as in TB -- by categories such as Sender, Recipient, date, attachment included, etc?

(b) will I be able to copy and paste from, or print out, individual emails?