11.40.0.2 (9-23-2013) Fixed case 77077: Make Horde save sent mail by default with Dovecot.
11.40.0.7 (10-16-2013) Fixed case 79889: Fix Horde sent mail folder prefix.
And as a result, these changes have had "unintended consequences." If you use Horde webmail and have noticed the following error when sending email
The folder "Sent" was not created. This is what the server said: Client tried to access nonexistent namespace. (Mailbox name should probably be prefixed with: INBOX.) Message sent successfully, but not saved to Sent.
Try the following steps to recreate the "Sent" folder so that Horde can access it.
1. Login to the mailbox though IMAP
2. Click on "Mails" and then select "options" tab.
3. Select "Personal Information" link under the general option.
4. Then select the check box "Save sent mail" and select "create a new sent mail folder" option.
5. Provide the name to the sent items folder and Save the changes.
This will make the sent item folder into the mailbox.
Alternatively, one user has reported that simply selecting the existing "Sent" folder from the dropdown (within Horde's "Options") fixes this issue.
If neither of these fixes work, or you have any other issues, please let us know. We're here to help!