Thunderbird Archiving

When I archive my emails, one only of my email accounts returns the below message. All my email accounts have the same settings - I have no idea to correct this - suggestions would be very wecome!

The Thunderbird mailbox contains messages that are located on an IMAP server. Therefore, only emails from the local Thunderbird cache have been archived which are not necessarily all emails that exist in the IMAP mailbox on the server side.

I get that as well using Thunderbird Portable.
I suspect it’s because of the way that Thunderbird handles IMAP, only downloading the basic message & header, not any attachments.
Look at the account settings in Options | Account Settings | Syncronisation & Settings, if you set to download everything, regardless of size, sync all messages locally and [ ] keep all messages in all folders I think you’ll find the message goes away.
I just ignore it, Mailstore seems to hold all I need when I restore messages, but it’s all down to how critically you need to preserve your email

Thank you for the suggestion DuddleBB, sadly it did not resolve my issue.
I guess I’ll have to copy you and ignore it!

thanks for the awesome information.

Hi all,

yes, this measn that Thunderbird handles IMAP in a way that we cannot retrieve all mails. So the archive won’t be complete.

But instead of tinkering with Thunderbird settings to minimise the issue, I’d like to offer an idea to completely avoid it:

IMAP is a synchronising protocol, which means, that Thunderbird and your IMAP provider mailbox are always keeping in sync. So in your provider’s IMAP mailbox, there is the same content.
So instead of archiving from Thunderbird, why not create a different archiving profile in MailStore Home:
Server via IMAP.
MailStore Home would then archive directly via IMAP from your provider.
This also means that even if Thunderbird would be defective at any time, or be closed for weeks and not fetch new information, MailStore Home can still retrieve the newest mails.