Are you really willing to risk not only your email deliverability, but also the reputation of your IP address and your company? Even if you find the light after purchasing or renting email lists and decide to only email those who have opted in with your company, it'll take you months (or maybe years) to get your Sender Score up and rebuild the reputation of your IP.
Did you know there are organizations dedicated to combating email spam? Thank goodness, right? They set up a little thing called a honeypot, which is a planted email address that, when harvested and emailed, identifies the sender as a spammer. Similarly, things called spam traps can be created to identify spammy activity; they're set up when an email address yields a hard bounce because it's old or no longer valid, but still receives consistent traffic. Fishy, eh?
Will people understand what you’re trying to say? It’s usually better to avoid topics (or opinions) that are complex if many people are extremely passionate about them. For example, sharing almost any opinion about immigration policy is usually a bad move, unless your audience is unusually homogenous. You could agree 99% with someone and still piss them off by using the wrong term just because they have such a strong “either you agree 100% with us, or you’re our enemy” mentality. I once pointed out that I think it’s unacceptable to capture and torture people for years—especially if they aren’t charged with any crime, there’s no evidence they’ve done anything wrong, and they’re children. I got several emails back from people saying, “you have no idea what you’re talking about” or “you should stick to marketing and leave politics to people who understand it.” They took it as commentary on geo-politics. I just said I’m not okay with pointless torture of children. I thought we’d all agree on that.
Take advantage of the email template designer or upload your own. There are also tools to segments lists and personalize emails with all your contact data. The A/X testing feature allows you to test up to ten different versions of your email before you decide which one stands out as the best. A campaign comparison tool pits your previous campaigns against the current one to give a complete picture.
Keep the subject line and pre-header short: The subject line is crucial. Keep it short so the reader knows exactly what the email topic is about. And the pre-header text (also known as snippet text), don’t let it go to waste by using “To view this email in your browser…”. Instead, summarize the email or include a call to action (i.e., Use “FREESHIP” to get free shipping).