If this is a one shot deal for Chaim, and it seems like it is, I would absolutely not do a bulk email to all of the Knesset members.
They talk to each other, and they will soon realize it was a bulk email.
A serious person sends a letter by mail, certified. A certified letter gets attention. Chaim needs to hand pick the Knesset members whom he feels will most likely be in favor of him obtaining Israeli citizenship. Perhaps choose ten or 12 out of the fifty Knesset members for personal letters. The letter should say something positive about the Knesset member.(This makes is personal, and is more likely to swing them over to his side). The letter should be succinct, and no longer than 2 pages. The letter can be followed up with an email. Your letter is basically the same, with some minor adjustments depending on who the Knesset member is. So, its not a big deal to personalize it. It's worth the small amount of extra time.
The other Knesset members, who you don't expect much support from, can receive a bulk email, and hope for the best with them.
Hope this helps,
The Shadow