[IRONY]Yeah. Much more likely that he'd only reply to emails with "viagra" or "bigger" or "nigeria" in the subject than mere Mac-related emails.[/IRONY]
That's /sarcasm not /irony
Technically, it was both. Sarcasm is a subset if irony. Right in Apple's own dictionary application:
sarcasm |ˈsärˌkazəm|
noun
the use of irony to mock or convey contempt
A grammar nit-picker got it wrong - how ironic!
Irony has a much broader definitition than most grammar nit-pickers know. If someone says "pull my finger", and you pull his finger, and he burps instead of farts, that is irony.