...and even if you have an audience using a single browser, you can't count on them all running same res, etc, so the observations from TedPride et al (above) --IMO-- are wise.

However, jdb, you wrote "the text www takes more space than aaa or iii."

But, pedantically and just FWIW, you could use css to have mail addresses rendered in a "Fixed width font" (think console fonts; tty; typewriter). In that case, the width needed for "www" would not differ from that required for "iii."

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Update ( apology/reply to jdb's, immediately below): Yep, agree. To some extent, my comment was OT or redundant, anyway, but someday, some SoPW may find this thread and miss the exception to the general case you asserted.