No, but it is unwise to put in very many. Mail servers impose limits on the
number of recipients you can have for a message, so you want to make sure
not to exceed the limits posed by your server. DL's are not robust and
become corrupt very easily. The more members it has, the more quickly it
will become corrupt. Use DL's only for a small number (<25) of recipients,
so it won't be such a big chore when you have to recreate it from scratch
(which you will, sooner or later).
