Messages being marked with label "unknown-0"

My mail is periodically acquiring labels in the form "unknown-x" where x is a single digit number. If I remove the label from the affected mails I can remove it, but in time the another message will appear labelled unknown!

I do not know what is causing the issue but suspect that it may be related to my mail provider Dreamhost, since I think the problem only affects Dreamhost addresses and not my GoogleMail email accounts.

Dreamhost have a system where mail older than 45 days is moved from the inbox to a folder called old-mail. I am accessing the mail server via IMAP and am subscribed to all available folders.

Any thoughts?

Opera 11.52 on Win7

When you see a label like this, right-click on it and goto its properties. On the IMAP tab, check to see if "unknown-x" is set as the IMAP keyword.

If it is, it probably means the IMAP server is adding the keyword to certain messages and since Opera supports IMAP keywords, you get the label.

One solution is keep the labels and just right-click on the "Labels" access point header in the mail panel, goto customize and uncheck the labels to hide them. Since you said it's a single digit, at most, you'd have only 10 labels to hide.

I think Opera has an internal blacklist of keywords to ignore as far as label-creation goes. Maybe "unknown-x" can be added to it. It might help if you ask your mail provider about it and ask them what it's for (while pointing them to this thread) just so we know for sure.

Originally posted by Ampa:

Dreamhost have a system where mail older than 45 days is moved from the inbox to a folder called old-mail.

Are all the messages that show up in these labels in the "old-mail" folder on the server?

Indeed, if these keywords aren't *too* likely to be used as normal manually added keywords, we can add them to the blacklist.

Lately there's even an IANA registry for known keywords, but it is still rather sparsely populated: http://www.iana.org/assignments/imap-keywords/imap-keywords.xml

Originally posted by burnout426:

...goto its properties. Check to see if "unknown-x" is set as the IMAP keyword.

I checked the properties and the label, in this case 'unknown-6', is indeed listed as the IMAP synchronization keyword.

Originally posted by burnout426:

...right-click on "Labels", customize and uncheck...

I think it is always a single digit but since I tend to tidy these spurious labels up as soon as they occur, I don't have much of a track record to examine! Still, this could be a useful work around - thanks.

Originally posted by burnout426:

Are all the messages that show up in these labels in the "old-mail" folder on the server?

Yes. I don't think this has ever happened on a message in the inbox, but again the fact that I've removed the labels in the past is unhelpful in tracking the issue down! I shall leave the labels in place (for now) to try and spot the pattern.

My concern is that Dreamhost is objecting to Opera's labels and somehow corrupting them, resulting in something that Opera no longer recognises. I am only just exploring the power of labels, but a quirk like this is rather off putting!

I shall get in touch with Dreamhost as suggested to see if they can shed any light on the subject.

Thank you for your thoughts so far

Originally posted by Ampa:

My concern is that Dreamhost is objecting to Opera's labels

If you don't set a keyword on labels you create and remove the keywords from the default labels, there's no way for the server to know that you even use labels.

I wrote to Dreamhost...

I use Opera 11 to fetch my email via IMAP.
Periodically messages are labelled with an IMAP keyword in the format "unknown-x" where x is a single digit.

At present I have 3 messages labelled 'unknown-6' and one 'unknown-4' [Details supplied]

I am trying to track down where this issue originates, and have begun a discussion on Opera's forums at http://my.opera.com/community/forums/topic.dml?id=1133742&t=1319649027

I wonder whether Dreamhost support can shed any light on what is going on!

And they replied...

Thanks for contacting us. I have looked at your issue and is it affecting the filtering of your mail or mail delivery?

And a little later...

I reviewed your support ticket and checked with our mail admin. This looks like it may be an issue with your email client.

The full list of labels we're sending the client for your affected directory (old-messages) is this:

0 $Label1
1 $Label5
2 $Label4
3 $MDNSent
4 $Forwarded
5 $Junk
6 $NotJunk

It looks like your email client doesn't seem to like #4, or #6.

All the non-standard message flags are called keywords in IMAP. Some clients use these automatically for marking spam (eg. $Junk, $NonJunk,
$Spam, $NonSpam keywords). Thunderbird uses labels which map to keywords $Label1, $Label2, etc. Dovecot (our mail server) stores keywords in the maildir filename's flags field using letters a..z. This means that only 26 keywords are possible to store in the maildir. If more are used, they're still stored in Dovecot's index files. The mapping from single
letters to keyword names is stored in dovecot-keywords file.

We've regenerated the keywords file which will hopefully help.

Yikes! I am not really sure that I understand the implications of what they are telling me! Can anyone explain in simpler language?

They're saying that they think that the server adding the $Forwarded or $NotJunk keyword to a message is something Opera doesn't like. But, I just added those keywords to a message and Opera or the server didn't add any unknown-x keywords to the message and I didn't get any labels created from them. But, that's testing with imap.1and1.com, not with your server.

Originally posted by Ampa:

We've regenerated the keywords file which will hopefully help.

Let us know if that helps or you see them again.

You could create 2 labels in Opera: one with $Forwarded set as its keyword and the other with $NotJunk set as its keyword. Then, you could add a message to both of them to see if it triggers the creation of an unknown-x label. When you're done testing, you can right-click on the message in the labels and choose "remove from view" to remove the keyword. Then, you can delete the labels.

Thanks for the reply - I shall try to follow your suggestion a little later.

In the mean time, two more messages have just been added to my unknown-6 label view...

Both messages originate from 10th Oct, so that rules out my theory that the issue is triggered by messages being moved from the inbox to the old-messages folder, since these messages are only 18 days old so will not have been archived yet.

Another new label has appeared unknown-5 but intriguingly there are no messages displayed in this view! I right clicked on the label (in the label section of the mail panel) and selected delete - the label vanished, and was then immediately recreated (again with no messages in the label view)!

Still very puzzled!

Download the Opera installer and use the "standalone installation" option to install to a folder on your desktop. Setup the IMAP account in it (do not import anything) and see if it also gets the unknown labels.

I just did a new install of Opera as you suggested, and added my main email account using IMAP.

The same 2 messages in the inbox were immediately labelled unknown-6

I also tried creating labels ForwardedTest and NotJunkTest with the keywords $Forwarded and $NotJunk respectively. I assigned a message to each, but this didn't trigger the addition of any messages to unknown-x labels. Then I subscribed to the old-messages IMAP folder and 3 messages were added to NotJunkTest, nothing to ForwardedTest, and still nothing new in unknown-6 or unknown-4.

Originally posted by Ampa:

I just did a new install of Opera as you suggested, and added my main email account using IMAP.The same 2 messages in the inbox were immediately labelled unknown-6

Did you remove them from the label in your normal Opera first? Otherwise, the label would just sync in the standalone Opera.