To make the MAP quota always visible left on the statusbar the configuration must be changed to set a threshold for
it.
Set the mail.quota.mainwindow_threshold.show to value 0 using the configuration editor.
The configuration editor is found at the bottom of the settings page.
It could be that after updating Thunderbird to version 115+ the unified folders are missing some accounts.
This can be fixed by deleting a file and a directory content.
rm "${HOME}/.thunderbird/Profile/virtualFolders.dat"
rm "${HOME}/.thunderbird/Profile/Mail/smart mailboxes/"*
The latest Thunderbird version (> 128) supports CardDav address books.
Create a new CardDav address book and only 2 fields are required to fill in.
The Username and Location where the username is not applicable and
the location URL is referring to a Google-account.
The location for a Google account is as follows:
https://www.googleapis.com/carddav/v1/principals/<google-email-address>/lists/default
Where <google-email-address> is the yourusername@gmail.com.
Continue the 2-factor Google authentication process and the address book entry is created.
Immediately go to the Properties of the address book (right-click contextmenu) and
set it to Readonly.
Make Dolphin get the context menu 'Send To' with a 'Mail Recipient...' option.
Allowing for multiple files to be attached when this is no already the case.
Create file /usr/share/kservices5/ServiceMenus/thunderbird-mail-recipient.desktop or
${HOME}/.local/share/kservices5/thunderbird-mail-recipient.desktop respectively
for all users or a single user having the following content.
# Insert the following content into the file.
[Desktop Entry]
Type=Service
Actions=SendToMailRcp
Encoding=UTF-8
MimeType=application/octet-stream
X-KDE-ServiceTypes=KonqPopupMenu/Plugin
X-KDE-Priority=TopLevel
X-KDE-Submenu=Send To
[Desktop Action SendToMailRcp]
Name=Mail Recipient...
Exec=thunderbird -compose "attachment='$(echo %F | sed 's/\\ \\//,\\/\\//g')'"