Indeed Postal does offer both of the mail features you described.
Satrina Buff Frames can do what you want for the buff icons, just depending on the extent of the changes you want, it may not be the most user friendly for just basic visual tweaks.
Elkano's Buff Bars is all well and good, but I feel that due to display in a bars form, when you start getting substantial numbers of buffs particularly in a raid setting it does take up far too much room.
An icon display will be far more compact, and for most buffs you do not need to see any name on them, even an abbreviated one.
PowerAuras amongst other addons provides a more appropriate display should you really need highlighting or awareness of specific ones.