OK, so you are not in any way targeting these eMails, just sending out what will in the majority be considered random-spam, and hope that a "trick" or two will get you a job?
I think you have to start with some basics:
- A great cold calling campaign would result in a pick-up/click through ratio of 2% to 3%
- Lets say they open your eMail, then the current average rate to telephone interview is below 1 in 30
- The average candidate needs 5 telephone interviews to get one physical job interview
- You'd be doing well to get one job offer per three physical job interviews
Hence, according to my calculations, you need to send at least 22,500 eMails to get one one job offer! Where are you going to find or buy 22,500 eMail address that all work?
Unless your target job is in eMail marketing, I suggest that any tactic will in the scheme of things be wasted time, as opposed to picking 50 target employers and doing better research on them. Getting the name of the hiring manager for your ideal job in that target company, and then writing to them. Then you could validly write "How I can add to your company" as opposed to trying to trick someone who you later expect to employ you.
Get real now about the practicalities of this scheme, and get employed quicker - Good Luck!