A lot of marketers promote products or build websites in a number of different niches because obviously the more niches you are in, the more money you should make. However this can take up a lot of your time, and so building and maintaining email lists in each of these niches will eat up even more of your time.

Just building a list and getting the ball rolling can involve a lot of effort because you need to create an opt-in form and/or a lead capture page, and then you have to drive traffic to this page containing your opt-in form. Then you need to ensure that you provide good quality content to your subscribers so they stay subscribed and are therefore receptive to your offers when you do pitch a product.

Now obviously if you have multiple email lists, you are looking at a really heavy workload, and even if you outsource some of the content writing, it can still be both costly and hard to manage.

This is why I don't personally think it is vital that you build an email list in every niche, and indeed there are certain instances where it may actually result in fewer sales. For example, in small niches where there are only one or two decent products to promote as an affiliate you're probably better off sending traffic directly to the sales page of these products. This way you don't have to go through the lengthy process of building a list and developing a good relationship with your subscribers through providing good quality content.

There are also niches that are literally flooded with other email marketers, and so every email you send will often be competing with several other marketers' messages, so your open rate will be a lot lower. The particular niche I'm talking about is the internet marketing niche. I myself used to market to this niche and made small profits, and it was only after I started building lists in other less competitive niches that I realised how much time and effort I'd wasted marketing to other marketers.

Another way to make decent money from affiliate marketing without building a list is through promoting products that pay commissions on a recurring basis. These are products usually involving monthly or quarterly payments such as web hosting, autoresponders and membership sites. I love focusing on promoting these sites because each customer or subscriber can reward you for months or even years in some cases.

Similarly if you are an SEO expert you could focus on building up a network of websites and sending traffic to particular products directly from your web pages. The more sites you build, the more money you will make.

So to sum up, in an ideal world of course you should build up huge lists in every niche you enter, but the reality is that most people do not have the time to do this, and in fact you can make just as much money not doing so in some instances.