So long as the tables are 'well-formed' they won't automatically invalidate your code.
There is (currently) no validation procedure* (in the pass/fail sense) whether or not a site uses tables 'correctly' (i.e. solely for tabulated data).
The push to use CSS for layouts is a related issue that goes beyond code; one that is concerned with the creation and promotion of a meaningful, 'semantic', x-platform net/web.
(* There is
this though.)
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Mailto links are generally a bad idea for several reasons.
Mailto links rely on the presence of a functioning email client on the visitor's machine. These aren't always available on 3rd party machines (internet cafés, schools).
There's also email harvesters controlled by spammers are becoming increasingly able to read the contents of even encrypted mailto links which means that mailto addresses will end up receiving sh*tloads of spam.
Third issue (and probably as a result of either knowing or not knowing about the previous two issues), mailto links scream 'amateur'.