So I went back and read the first few letters that said
Some shit about a message you left
Oh shit! That's not a E, that's an A!
This dude wants to leave me a 'massage,' he's gay!

from Eminem – Canibitch Lyrics on Rap Genius

Meaning

Canibus reportedly sent Eminem threatening/provoking letters, and one typo proved a jumping point for Eminem to poke at Canibus’s sexuality.
I think this is a joke.

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