imap message flags/tags

is it possible to set a custom flag/tag to an email, that is stored in an imap server. This is very helpfull if you access the imap-server from different clients. With this you can classify the email’s with “later” or “waiting for answer” and filter for that…
While testing with my cyrus server, I did not find a solution. I found the categorie’s but I think this is a local feature not synced to the imap-server and therefore not useable for more than one client.
Now I use thunderbird, the tagging is good, but the carddav/caldav features are bad…
Is there a way to get this explained flag/tag feature storing at the imap-server (in my case cyrus) work?

Thank you for your help in advance!

Hi, this is unfortunately not possible, you can use the standard flag (follow up), to mark messages as flagged, but you can’t create a custom flag for your messages.

As you’ve noted you can use categories which however are only synchronized when using eM Client, e.g. you can use them on another device using eM Client, but you won’t be able to display them in your webmail.

Or you can create custom IMAP folders and use a custom rule to move your messages into this folder based on a subject, sender etc.

Hope this helps,

Hello Paul,

now I understod, that the categories are also synchronized over the imap server (the categorie-information is stored on the server), but only available for emclient`s. is that right?
I’m going to test it :wink:

Thank you for your quick answer… and a happy new Year!

Yes, the category information should be included when synchronizing the messages with your server.

Hope this helps, happy new year from eM Client as well!

Dear Paul,

I finished testing… the category is not in sync on both clients, so the information is not stored at my cyrus imap server (2.3.18)?!?

  1. fresh installation of em client on a second win7 client
  2. changed category for one message at client 1
  3. connect to imap-server at client 2
  4. no category information available ;-(((((((

What went wrong? Is a special cyrus configuration neccessary?


I did some tests with thunderbird and em client, and look direct at the server Port 143 which flags are set for the test message…

  1. flagged flag: thunderbird and emclient both i.o.
  2. special user flag: thunderbird i.o., em client no gui control as discussed i.o.
  3. category: em client, no additional user-flag at cyrus… not i.o.
    cyrus ha sthe capability to store user defiened flags/categorys, name it how ever…

While setting the category the em client seems to sync the message flag wiht the server, the same infomation in the protocol as by the flagged flag?
Any idea?


Hi again Jürgen, I’m afraid this might be a server issue, as it seems your server clears the additional flags, thus can’t be synchronized, however please navigate to Tools > Settings > Advanced and turn on “IMAP” logging for the problematic account,

  1. Save the settings
  2. Restart the application
  3. Replicate the issue
    After the issue reoccurs, please go back to the advanced settings window and click on “Send logs” and send the logs to my email, with a reference link to this forum topic.

You can also enable the logging on both of your computers, and send it to me both.

Thank you,

So, eM Client does not support IMAP keywords like Thunderbird does, correct? If so, it’d be a critical feature request for me. It would be a pretty high price to move from Thunderbird to eM Client if I have to lose all categorisation for years of e-mails. An “eM Client only”-categorisation feature (stored serverside or not) is not attractive either, I fear.

I hope this will be a nearly solved feature request!
I ́m waiting hopefully for this with (i bought some licenses)… it is a must have not a nice to be!
But for the rest of em Client they have done a very good job :wink:
Thank you!

Hi again, eM Client does support IMAP keywords partially, but unfortunately we do not support the Junk/NonJunk flags which you’ve referenced.
This feature is unfortunately not currently on our roadmap to upcoming updates, maybe with future releases of eM Client.

Thank you,

The $Junk/$NonJunk-flag system is indeed reused by Thunderbird to also set flags for other categories, as I understood it.

You say that such a feature is not on the roadmap. Would you kindly explain why not? We requested the feature with good reason (i.e., to not lose years of categorisation data). I have not yet purchased eM Client. If I do purchase a license, would that be motivation enough to implement the requested feature?

Again, this feature is very critical for me (and others, clearly).

Hi again, this not a widely supported feature on mail servers and the use is limited for some servers only.
It’s also due to unreliability of the feature, as some servers can create a chaos when using the $Junk/$NonJunk-flag.

However as you’ve referenced other categories in TB, this is something different as Thunderbird using about five category colors which are behaving as labels, these labels are basically identical or very similar to eM Client’s categories. We’re considering improving eM Client so the categories are kept during import from Thunderbird.

Thank you for understanding,

Hi Paul,

There is a “dovecot-keywords” file in my Maildir on the mailserver, which contains:

0 Junk 1 NonJunk 2 $Forwarded 3 $MDNSent 4 $label3 5 $label1 6 $label4 7 $label2 8 $label5 9 wachtend\_op 10 volgende\_taak 11 ooit\_misschien 12 hobby 13 studie 14 persoonlijk (...)

Labels 9 and following I recognize. Thunderbird must’ve added them (via dovecot, of course). I see five labels that Thunderbird could possibly use as categories but I never used those or knew about “the five”. I’m not a server magician; I run plain dovecot on a Ubuntu server. I know both software products are popular and I didn’t explicitly enable the “keyword feature” or something. In other words: I think it’s more widely supported (these days anyway) than we may realize. Anyhow, how does eM Client store e-mail categories on the server? Can I add a header to a message denoting its category? If so, I might fix convert message categories from within Thunderbird.

Hi again, unfortunately if you’re using a dovecot server, this server does not support category sync, the categories can be synchronized with several mail servers, especially Exchange and IceWarp (IMAP).

Category synchronization is not standardized as each server is using their own “thing”.

As I previously mentioned we’re currently considering adding label import for Thunderbird, this however would not apply to the Junk/NonJunk and other IMAP keywords you’ve mentioned.


Well, if dovecot does not understand category sync, I really don’t know why my actual categories ended up in that dovecot-keywords file.

Anyhow, how does eM Client synchronize categories with IMAP servers, then?

Category synchronization is only supported on the above mentioned servers, the problem is category synchronization is not standardized, each server is using different flags or different method for synchronization, and only Exchange has a standardized way of how to sync the categories with the server, sync with other vendors is not supported due to missing sync option with the mail server or due to lack of support in use with the protocol.

Hopefully this can be improved with future releases,

We were really considering using eM client for our company - we almost bought it for a lot of users. But then discovered this issue on the last moment. Without category/tag synchronization with mail server - it’s a no go. Funny you think Exchange and some other obscure IMAP server software as standard and disregard how other not-proprietary services work. But on the bright side - we might come back from time to time looking if you have decided to implement IMAP keywords support (RFC5788 nowadays) for category/tag synchronization.

Hi, as I previously suggested, there’s no standardized way for category synchronization, so unless mutual agreement with the mail service is reached about using a certain standard for synchronizing these items, it is not possible for the client to synchronize the categories.


So RFC5788 is not standard? How Courier, dovecot, Thunderbird and probably some others have dealt with this for long time is not standard? You see some clients and “mail services” have already “agreed” on how it should be done. You could do it the same way, you could do it differently - but the facility for storing this data on the server exists and is pretty much agreed on considering there is an RFC for it.

And I bet your customers wouldn’t care if you do this in a standard or non-standard way - only thing they care about is a way to tag their e-mail messages so that those tags are seen by others using the same mailbox. Yes it would be a plus if this works over multiple email client apps but it would be good enough if it works in at least eM Client when using the same server/account at multiple installations.

Your users need the feature now not in some distant future when some magical outside entities have officially agreed on what is currently de facto standard anyway (might not be best solution, of course, but the solution exists nevertheless).

Consider thinking about it. Think about it. I cannot write a plugin for your software - so I need you to think more. Or maybe create a extension framework for those who need extra functionality now - that would be a solution too.

Unfortunately it is not a standardized way for synchronizing categories, it’s a specification for using this method, however still just a proposition for standard (