I am using the Thunderbird-Extension "Send later" to, well, send some emails later. One annoying thing is that it saves the message in the Drafts folder as an unread message. Does someone have an idea how to change this behavior (except for asking the author of "Send later")?

Spontaneously, I thought of somehow abusing filters to achieve this behavior. The problem here of course is, that one cannot run filters automatically after one *sends* an email but after one *receives* an email.

Of course, I see the option of just right-clicking the "Drafts" folder an then clicking "Mark Folder read" but I think there should be an automatic way to do this.