Q:

Meaning of ように in this sentence

吉野家は「私たちが出した広告ではありません」と話しています。そして、うその広告に書いてあるアドレスにメールを送らないように言っています。
  Yoshinoya say that "It's not an advert that we put out". And, they are saying it so that you don't send mail to the address that is written in the fake advert.

I'm sure I must have mis-translated ように here because my translation sounds like a very strange thing to say. The only other translation of ように I know is 'like'/'in a way that' etc. which seems to make even less sense.

A:

「(Verb Phrase) + ように言{い}う」

means:

"to tell (someone) to (verb phrase)"

Thus,
「メールを送{おく}らないように言っています」 means:
"is/has been telling (us/everyone) not to send mail"
This 「よう（に）」 is extremely useful because, besides 「言う」, you can use it with any verbs that express requests, orders, recommendations, suggestions, advice, etc.

