Re: [PATCH v4 1/3] send-mail: improve checks for valid_fqdn

> Yuck, can we do something about this overly long mess?  
> 
> If use a temporary $subdomain = '(?!-)[A-Za-z0-9-]{1,63}(?<!-)',
> would it make it easier to spot the repetition in the structure,
> i.e. /^$subdomain(?:\.$subdomain)*$/ and make it less error prone
> when somebody has to touch lines around here, or something?
> 
> But other than that, looking good.
> 
> Even though this allows "foo.local", on "darwin" it is still not
> allowed, which sounds like a regression-free change