I own a few niche sites wherein I recommend various products related to the sites' foci, and provide monetized links (usually to Amazon) for people to buy those products.
On occasion, I get emails from product manufacturers who want me to test, review, and promote their products. They typically begin with something along the lines of, "We noticed that you evaluate and review [type of product] on your site, and we were wondering if you'd be interested in reviewing our [model of product]." A short description, a link, and a statement that I would get to keep the product regardless of the opinions I express in my review, usually follow.
I also occasionally get emails asking whether I'm willing to enter into a direct advertising arrangement with a company for some product or products. Usually these emails also include an offer of a sample or samples of the product(s) in question for me to test before I commit to accepting the advertising deal.
By way of background, I'm about as anti-spam as a person can get. I've been a Spamcop reporter since shortly after Julian Haight founded the outfit, and I have reported close to 100,000 pieces of spam since then. Just the fact that I didn't ask to be contacted is enough to make me think about reporting a piece of email as spam.
But even being as anti-spam as I am, I don't report sincere requests for product reviews or advertising inquiries as spam as long as the emails are polite, well-written (with some slack extended to those for whom English isn't their first language), and include an unsub link or some other easy means of not being contacted again if I'm not interested. At the risk of being self-centered, I think most people who do product reviews or who accept product advertising probably feel much the same way.
That being said, you should be aware that there are morons out there who report anything that they don't want to read on a given day as spam. I frequently have to contact ISPs and RBL maintainers to point out that an email from one of my users that their user reported as spam was actually a legitimate invoice, a proposal that the user requested, a newsletter that they opted into receiving, a collection notice, or some other unquestionably legitimate piece of mail. Many users are too trigger-happy when it comes to reporting spam.
Similarly, some ISPs and RBLs are also trigger-happy when it comes to blacklisting a sender. Some will blacklist a sender based on a single spam report. And more often than not, the blacklisting applies to the mail server's IP address, not to the sending domain. So if you're hosting multiple sites or clients that send mail through the same IP, all of them will find themselves unable to send mail to recipients whose email providers use the RBL in question.
As I mentioned, I believe that most reasonable reviewers and tech writers would not report a well-written request for a review as spam. But some might: And if they do, you run the risk of your mail server's IP address being blacklisted.
If that were to happen, the removal process would range from very easy (or even automatic), to nearly impossible, depending on the maintainer. Some maintainers automatically remove IPs after x-number of hours or days, some provide automated removal forms, others manually review requests but are reasonable about them, and others will never remove an IP or have no way to even contact them about it.
In summary, if you choose to do what you're considering, be very careful about the wording of the email. Run it past a few friends and colleagues to see if it comes off as "spammy" to them. Be pleasant and polite, but also brief and to the point. Also provide an easy way for the recipient to opt out of ever hearing from you again. You really don't want a recipient reporting your email because they got up on the wrong side of the bed that morning.
Also consider using a separate domain with a dedicated IP address rather than one that handles mail for other domains, and send mail through that dedicated IP. Some RBLs will block entire netblocks, but most do not. I require clients who want to send even double opt-in automated mailings to have dedicated IP addresses and to send mail through them. That at least protects the rest of my users from winding up on RBLs because some moron falsely reported the mass-sender's legitimate mailings as spam.
