This is a somewhat updated version of the Original Easy Mail to fix some issues, as the author has been absent for...well, nearly a decade. No further maintenance is intended (but it seems to happen anyway).

Current changes over the original are listed in file changenotes.

notable features:

planar fragments are handled better (better than vanilla, and original mod)
less buggy handling of attachments in general
a 'clear' button for the 'send' tab
new 'enhanced' item overlay mode. colorful! Also now has a higher contrast version and color override mode, with a helpful color picker and some preview squares! Left squares are for the colors without override mode, right squares are for the colors with it on. If a text field isnt filled the color component is inherited, based off whether enhanced and high contrast are on.

known issues:

error that happens when sending mail / taking all, without sufficient room. difficult to fix, is harmless. if you get a message about an overflow container, clear up your inventory and go place an item in a dimension.
the overlay is missing/misaligned the first time it is loaded. this is due to incorrect values reported by the game's native code when a UI frame is first created. there is no way to correct this, so just reopen your bags.
sometimes the native UI reports all zeroes for every value. only fix is to reopen bags. a helpful warning message will show in place of the attachment list when this happens.

Easy Mail fixup