The reason I ask is -- the maximum length of a valid email address is actually 256 characters (or 254, according comments in the PHP function is_valid_email_address(...) that I found on the Internet at http://code.iamcal.com/ and use myself).
In my own PG DDL, I define email addresses like:
contact_email_addr varchar(256) NOT NULL,
FWIW, I stay away from varchar limits that are more than a "suggestion". Generally speaking it's just not worth limiting to something like 50, then the business decides they want 60, then 70, then... I still use varchar to ensure the database can't get DOS'd with garbage, but I'll just set something like varchar(100). That said, if there's a defined limit for email address length, might as well use it...
Disclosure: I'm a PG newbie (and a relative SQL newbie, too), and not familiar with the DEFAULT ":: notation in your DDL.
The :: is a cast that was presumably added by Postgres when the default was assigned. It's equivalent to DEFAULT ''. I definitely don't like defaults like that... if you don't know what the email is then it should be NULL. Or to put it another way, having a default set largely defeats the purpose of NOT NULL (IMHO). --