The \starttable syntax is deprecated and should thus be avoided for new
documents. That's why I present a solution using natural tables, also
called HTML tables. Since natural tables are very verbose they can be best
combinded with the database module. That allows very easy and readable
syntax, but is less flexible. It depends on your requirements if the
database module makes sense in this case. The natural table setup is the
same in both cases.
For more simple tasks the tabulate tables might be sufficient.
\usemodule [database]
\defineseparatedlist
[NaturalTable]
[separator=comma, %% not necessary, already the default
before=\bTABLE, after=\eTABLE,
first=\bTR, last=\eTR,
left=\bTD, right=\eTD,
setups=s:NaturalTable]
\startsetups [s:NaturalTable]
\setupTABLE [frame=off, distance=5mm]
\setupTABLE [column] [1] [width=2cm, align=flushright]
\setupTABLE [row] [1] [style=bold]
\stopsetups
\starttext
\startNaturalTable
Name, Email
John, john1989@gmail.com
Bill, bill1990@outlook.com
Tim , tim1995@hotmail.com
\stopNaturalTable
\starttabulate [|p(3cm)r|l|]
\NC Name \NC Email \AR
\NC John \NC john1989@gmail.com \AR
\NC Bill \NC bill1990@outlook.com \AR
\NC Tim \NC tim1995@hotmail.com \AR
\stoptabulate
\stoptext

\starttable[|lw(4cm)r|lw(7cm)]. A small list of references are given here: http://tex.stackexchange.com/questions/2839/where-can-i-find-good-context-documentation/2938#2938 – Marco Daniel Apr 15 '13 at 17:01