Emails from recruiter's can be pretty hit or miss, and unfortunately have a fairly infamous reputation in the tech community. This is usually partly because of their often spammy nature, and partly due to a lack of interest in the jobs they're pitching.
I've been working on a fun little tool to 'lint' recruiting emails, running them through a number of rules to try and provide feedback on how to improve them. It's by no means fool proof, but does provide an effective first countermeasure against poor recruitment emails.
Simply paste an email into the left hand text area (or click on one of the examples), the text will be matched against a bunch of rules, and any warnings displayed. The rules are mostly inspired by emails that a few friends and I have received.