Remote content is not saved with the contents of the message. It is separately and temporarily stored in the cache. If/when the cache is cleared, the remote content must be re-downloaded from the server.

Thanks Stans. You have re-iterated the fact. My question is "What-if" i.e. Are there any problems in storing the remote contents along with the message (Of course, subject to the preference of the user, a setting).

Whatif Thunderbird downloads the contents (when the email is downloaded) and includes them in message itself?

The answer still remains, the remote content IS NOT stored with the message when the email is downloaded. It is stored temporarily in the cache. Your question implies that remote content is merged into the local copy of messages that Thunderbird downloads, but that is not the case. The remote content is NOT included in the stored message. The message is stored separately in mbox or eml files, while remote content for that message is kept in the cache temporarily. When the cache is flushed or filled with new content, the old remote content becomes locally unavailable. Once again, remote content is not included in locally stored messages.

Are there any problems in storing the remote contents along with the message

How do you intend to store remote contents along with the message?

Background: I use Thunderbird as a "offline" copy of my emails; once downloaded, the mails are deleted from the server.

I use Thunderbird in Windows. Here, the data are stored in an internal representation in the filesystem folder AppData\Roaming\Thunderbird\Profiles (The default location; can be changed) - sqlite plus other files. I imagine, the downloaded remote contents can also be stored here. Deeper technical part is to be designed (at this point, I do not know enough about the internal representation).

The background is the email is a HTML page. It is designed and composed by the sender with remote content. Your suggestion would require Thunderbird to basically set up a web server for the remote content to live on. That is a huge overhead. Otherwise Thunderbird could rewrite the email to not have remote content but local content. All good you could say because your objective is met. However if the email is signed or encrypted that just invalidates both of those things entirely. One of the things a signed email guarantees is the email has not been modified since it left the sender.

So I guess if you want to include the remote content you need to print it or convert it to a format that does not have remote content. Like PDF. The import export tools would facilitate that https://addons.thunderbird.net/en-US/thunderbird/addon/importexporttools-ng/?src=ss

You could file an enhancement bug in bugzilla, but I don't think it would get much traction. https://bugzilla.mozilla.org/

So once remote content is removed by the email sender or referenced servers (in days, weeks, months...?) that email will no longer look the same, no matter how the Thunderbird account is set up in advance? Nothing can be done to preserve the look and feel of the original email, other than taking a snapshot or PDF of every one as it's received? Really?

Not sure how to use ImportExportTools-NG to do as you suggest. How would I set that up?

Gary

Not sure how to use ImportExportTools-NG to do as you suggest. How would I set that up?

It may not be a fully automated solution. You will have to Show/Allow the remote content first and then export using the Add-on. You will have to do this periodically for the not-yet-exported mails. And I guess you will have to manage the exported contents - How do you intend to do that?