I don't think it sounds good, either. There's somehow something odd about it. First of all, while the letter is laden with errors and odd constructions, it seems to me as if someone has far too good a mastery of colloquial American English to have picked it up in Pakistan. The easy use of the contraction ("don't")wouldn't be something for a merely occasional non-native speaker, even somebody who used chat-rooms. I don't know any Arabic languages, so I don't know if these grammatical mistakes would be typical of an Arabic speaker or not. (People tend to preserve some of their native language structures when writing in a second language.)
I was also puzzled by Amrikan. Perhaps it was an attempt to spell Amerikan (remember, the radical left was always referring to America as Amerika).
And, as many people here have pointed out, the photograph is also a little disturbing. It's not possible to be sure that it's Pearl (who, furthermore, appears to be wearing the kind of nylon running suit or windbreaker jacket often favored by natives of Arab countries, judging from pictures I have seen). And the fact that the clean, smooth-looking hand holding the gun appears to be wearing a gold ring also indicates that we're not talking about crazed goat-herders here.