Some emails are harder to categorize as spam. In the last few months, I've gotten several complaints about browser problems. People report the blog looks bad on one browser and fine on others, or that they get weird popups. Some of these emails or comments are obviously spam; others harder to tell, but all seem to be based on the idea that we control that sort of stuff. We don't. Unless you're writing your own HTML templates, authors on blogger have very little control over such things. I'm sure only a small few of us do that.
Most strange things that pop up in your browser are on the reader's end and can be controlled with a hosts file. There are several sources of these around, but I use this one - the first one someone ever pointed me to. The site includes all the instructions you need to get started, but it's not really hard and you probably don't need to do everything they talk about.
Right now, some percentage of you are nodding in agreement, while the rest of you have Looney Tunes-style question marks in the air over your heads. What's a hosts file? Hosts is a plain text file that's put in a place reserved for Windows to look. The file is loaded when you open your browser and effectively presents a list of sites not to accept connections from! Presto - no browser hijacks, no redirects, no ads, no pop-ups (or, at least, lots less of them).
Example - the following entry 127.0.0.1 ad.doubleclick.net blocks all files supplied by that DoubleClick Server to the web page you are viewing. This also prevents the server from tracking your movements. Why? ... because in certain cases "Ad Servers" like Doubleclick (and many others) will try silently to open a separate connection on the webpage you are viewing, record your movements then yes ... follow you to additional sites you may visit.
Like everything else, hosts files aren't a perfect answer. Some of the companies they block do legitimate businesses as well as less scrupulous thing. Some of the companies that send you commercial (solicited, not spam) email may use one of these blocked sites as the way they handle your email click. Sometimes you'll find a site that you can't get to even though you're sure it's there and legit; usually, the site you're clicking from has gone through an intermediary in the hosts file. If you absolutely must be able to click on an email link that the hosts file blocks, or get to that check out service, edit hosts as administrator (XP and Win7 for sure; don't know about others), and delete just that entry (you'll know which site it is from the error box in the browser). Exit and restart the browser. You'll now be able to get to that previously blocked website.