I don't know that this is Sequoia specific. I think I saw this on earlier OSes. Mail. I have so much spam and just too much email. I've received warnings that I'm exceeding my amount so everyday I spend a little time deleting. I will select an email and search the sender, select all and delete. The problem is it only deletes for a limited time frame of maybe a month because I can scroll down 6 months or a year and I still find this emailer. This is so very frustrating. I want them gone from the beginning of time, but I don't seem to t be able to do that. I'm using comcast.