[rjzzleep]

edit: for those thinking that unsubscribe is a good idea. it's not. changing your email to a junkmail email before unsubscribing from services you don't need anymore is a better approach

for mutt users this is really easy to accomplish even with many mail accounts. create a macro file eg. ~/.mutt/macros:

    # have to be sourced on folder hooks
    macro index,pager ,a "<save-message>=$my_account_name/archive<return>"
    macro index,pager ,p "<save-message>=$my_account_name/pending<return>"
    macro index,pager gi "<change-folder>=$my_account_name/inbox<enter>" "Go to inbox"
    macro index,pager ga "<change-folder>=$my_account_name/archive<enter>" "Go to archive"
    macro index,pager gp "<change-folder>=$my_account_name/pending<enter>" "Go to pending"
    macro index,pager gs "<change-folder>=$my_account_name/sent<enter>" "Go to Sent Mail"
    macro index,pager gd "<change-folder>=$my_account_name/drafts<enter>" "Go to drafts"
    # vim: syntax=muttrc

now in your account hook do the following:

    folder-hook gmail \
       ' \
       set my_account_name=gmail ;\
       source ~/.mutt/macros ;\
       ....

afterwards type `T*,aG` and all your current email will be archived. from then on you can use the quick bindings for accessing all your mail with those shortcuts

[RHSeeger]

If it's a newsletter they are sending you legitimately (ie, you signed up for it) then you should not be marking it as spam; just use the unsubscribe link.

Marking emails as spam can have a negative effect on the company and, if they didn't do anything wrong, you shouldn't be hitting them with that.