E-Mail Applications: Unable to Write to Mailbox error

Mozilla Mail users may see the error: Unable to write to mailbox, please verify write permissions.

This is due to the fact that there is a mailbox folder size limit of around 2 gigabytes. This is similar to the Microsoft Outlook pst file limit of 1.8GB.

To regain access to your Mozilla mail, decrease the size of the folder. You can either move messages to another mailbox and/or compact the folder by right-clicking on the folder and choosing "Compact folder now".