> “LEVEL 3 is the last IRR operator which allows the use of this method, although they have discouraged its use since at least 2012,” Korab told KrebsOnSecurity

> “LEVEL 3 is the last IRR operator which allows the use of this method, although they have discouraged its use since at least 2012,” Korab told KrebsOnSecurity. “Other IRR operators have fully deprecated MAIL-FROM.” I'd prefer if we kept deprecated and removed as two different terms. It sounds like level3 deprecated it, and everyone else removed it. To me (and most definitions I can find) deprecated basically means "don't start using it, if you are using it stop using it, we will remove it soon but have not done so yet for compatibility reasons"