When you receive an email with plus addressing, you cannot find the email anywhere in RoundCube or Horde.
This issue is most commonly caused by a configuration problem. Please follow the steps in the following resolution section to fix the issue.
More information about Plus addressing can be found here:
First, verify that plus addressing is enabled for your email account with the following steps:
1. Login to the cPanel account that contains your email account
2. Click on the Email Accounts icon under the Email section
3. Click on the "Manage" button for your email account
4. Verify that the following option is currently set to "On"
Automatically Create Folders for Plus Addressing
NOTE: This option is enabled by default on account creation, but can be manually toggled to off.
Once you have verified that plus addressing is turned on, you must either subscribe to the folders or otherwise show them in webmail.
1. Login to Horde webmail for your email account
2. In the left sidebar, click on the "Folder Actions" dropdown
3. Click on the "Show All Mailboxes" option
You should then see the mailboxes that have been created for the messages sent with plus addressing.
1. Login to RoundCube webmail for your email account
2. In the left sidebar, click on the Settings button
3. Click on the Folders section
4. Toggle on the plus address folders that have been created