We all know the rule for “a” versus “an.” […]
So the sentence “I read a Guardian article” is straightforward.
But what about on Twitter? Any time you mention someone in a
sentence, you use their handle. Which means every name on Twitter
starts with @, a vowel sound. Do we count it? We tried to figure
that out this morning.
I say no — even if you’d say the “at” aloud verbally, in writing you should choose a/an based on the first letter in the Twitter handle, not the @ character. Tricky question though.