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Vintage Postcards heart Grammar

Help!!! Where are the grammar police when I need them!

I made a nifty new blog for my Mom.
All of these html courses are finally starting to pay off! I might even start a side business designing blogs:)

But... is it Elisabeth with an 'S' or Elisabeth with a 'S'. You would think that since 'S' is not a vowel you wouldn't say an. But say it out loud, 'Elisabeth with a S.' Something sounds off kilter! What is the grammar rule?