The default Thunderbird configuration defines 5 labels/tags with a “key” of the form $label1, $label2 etc. (full list below) which get displayed ats “Important”, “Work” etc. in the client. However, as regards the IMAP protocol the PERMANENTFLAGs set are the keys ($label1, $label2). Whilst these are stored and returned correctly via the X4 IMAP protocol they are not displayed in Webmail.
Some IMAP clients (e.g. Vivaldi) recognised these $label keys and display them with the same meaning as Thunderbird.
$label1 - Important
$label2 - Work
$label3 - Personal
$label4 - To Do
$label5 - Later
Thunderbird supports permanent flags in their own flavor:
** it uses $label1, $label2, etc. as permanent flags persisted on the server via IMAP for their default labels (Important, Work, Personal, etc.), combined with their own local labels index, in order to display their names and colors in Thunderbird; this means that the WebMail and other clients will not be able to use them.
** it also allows the user to use custom labels, which are persisted as normal permanent flags and they will also show up and be manageable from WebMail; also, labels set from WebMail will be visible in Thunderbird. In conclusion, as long as the user uses custom labels, and not the default Thunderbird ones, labels will be fully synced with the server and the WebMail, respectively.
When implementing labels support in Webmail, the decision was made to ignore the flags starting in “$” due to the reason explained above by user Jay - specifically because these are used by IMAP clients in combination with their own internal database.
For example, Thunderbird allows the user to modify the text associated with $label1 … $label5, and there is no way for Axigen to detect such a change, in order to provide a consistent user experience.
Our suggestion is, as well, to consider defining custom permanent flags that would suit your requirements, as these should be displayed consistently across all clients which support them.
thus allowing the user to configure if a label/flag is hidden or not (although defaulting the $ flags to hidden seems a good default), and also change how the labels are displayed in Webmail (possibly with some default mappings for common clients such as thunderbird).
