[development] translated text in module-generated emails?

[Derek Wright]

what's the right thing to do regarding the use of t() inside modules
that are generating emails?  specifically, i'm talking about wrapping
text that's going into an email (either subject or body) inside t().
i'm helping to maintain the user_status.module, and noticed this
comment:

// Probably don't want user emails to use t() since that might result
// in some unexpected languages being sent to users.

is that true?  is the party-line that all email text should be in
english, no matter what?  that seems a little strange.  it appears
that user.module wraps all the default text in t().  i don't
understand the harm in wrapping in t(), but i'm also mostly ignorant
of drupal's translation support and efforts.  can someone either
explain why this comment is true, or tell me it's all lies? ;)

thanks!
-derek