Even though rattling off “PR Tips” feels a bit copycat-ish (*bows to the master, Rafe Needleman*), here’s one…
You email a reporter. You get an OOO auto-reply noting a date of return. Please, for the love of whichever god you prefer, do not send attempt #2 at 8:00 AM of the aforementioned return date. Just imagine their neglected inbox. (Do it. I’ll wait.) OK then. Do you really think throwing another email to the top of the bloated inbox will be warmly received?
While it’s true that your first attempt is probably lost in the morass, give your recipient a few days before you go back to bat. You may earn yourself some valuable albeit unspoken consideration points.