A "thread" is a series of related email messages.
Ignoring threads and subthreads
The Ignore Thread feature is especially useful for mailing lists. It lets you skip reading the rest of a conversation you're not really interested in following, while still being able to keep up with all the other conversations.
To ignore a thread you select K (for "kill") keyboard shortcut. That will mark all the messages in the selected conversation as ignored. The ignored messages aren't deleted, but once you come back to the folder they won't be shown in the thread pane (by default). If there are further replies to the same conversation, these replies won't trigger a new mail notification., or simply use the
Ignore subthread works similarly to the Ignore Thread, but ignores only messages that are replies to the subthread starting from the selected message. This can be used to ignore otherwise interesting conversations that get off topic from a certain response.
What if I want to see my ignored threads?
If you decide you do want to see ignored threads, perhaps temporarily, you check. To again stop seeing ignored threads simply uncheck .
To un-ignore a single thread that has been marked ignored, select a message in the thread and uncheck.
See also: Blocking a sender