Email marketing was once one of the most effective ways of promoting commercial services of the companies and finding new customers but gradually, more people have turned to other marketing channels when they decide to research the net, trying to find bargains and great deals. The fact is that today, even subscribers to the newsletters would not examine all advertisements in letters.
There is a tendency to ignore commercial text links inside the newsletters, even if they come from reputable companies. If you look at PPC ads popularity and how firms invest in their paid advertisements heavily, you will notice that the admins of big firms may not tend to spend a lot of cash to include their ads inside emails and they prefer to use other advertising methods like PPC.