This is one of those fourth-, fifth-, or nineteenth-hand things and, as such, is not very credible. However, avoiding malls on Halloween doesn't cost anything and isn't a great inconvenience, so it wouldn't hurt to take small note of it. This was forwarded to me and I thought I would pass it on. At the moment this is not listed on the Urban Legend's website page.
***************************** Subject: Malls on 10/31 Hi All - I think you all know that I don't send out hoaxes and don't do the reactionary thing and send out anything that crosses my path. This one, however, is a friend of a friend and I've given it enough credibility in my mind that I'm writing it up and sending it out to all of you. My friend's friend was dating a guy from Afghanistan up until a month ago. She had a date with him around 9/6 and was stood up. She was understandably upset and went to his home to find it completely emptied. On 9/10, she received a letter from her boyfriend explaining that he wished he could tell her why he had left and that he was sorry it had to be like that. The part worth mentioning is that he BEGGED her not to get on any commercial airlines on 9/11 and to not to go any malls on Halloween. As soon as everything happened on the 11th, she called the FBI and has since turned over the letter. This is not an email that I've received and decided to pass on. This came from a phone conversation with a long-time friend of mine last night. I may be wrong, and I hope I am. However, with one of his warnings being correct and devastating, I'm not willing to take the chance on the second and wanted to make sure that people I cared about had the same information that I did.

-- Anonymous, October 12, 2001

Answers

I think this IS a hoax, but like you....it wouldn't hurt to NOt go anywhere near malls on the 31.

Am watching the service for the USS Cole...nice ceromonie.

Waiting for maintence man...will have to go soon.

-- Anonymous, October 12, 2001

This is about the fifth version I've seen of this letter, and I did see a link to one of the urban legend pages for it at one point.

I'm avoiding malls and crowds right now on general principles, and if I don't have something absolutely necessary to do (like visiting the dentist this morning) or going to work, I'm staying at home. I have plenty to do here (haven't even started fall cleaning!) so this is no hardship.

-- Anonymous, October 12, 2001

It never occurred to me to spend Halloween in a mall.

-- Anonymous, October 12, 2001

Brooks, some malls have parties for the kids; others have "trick or treating," where the kids can go store-to-store for candy or coupons.

-- Anonymous, October 12, 2001

I found the url for this at Countryside which says this is a hoax.

snopes.com

-- Anonymous, October 12, 2001

Thanks, y'all. Beckie, I'll send that on to the person who sent it to me.

-- Anonymous, October 12, 2001