Email marketing is probably the best ROI in the internet marketing stable. It can be used to keep in touch with your existing customers, as well as keep your presence up in front of prospects and former prospects. They often just need one trigger to buy!
The selection of the email list is very important and it cannot be stressed that a list of clients and prospects built up by your own company will always yield better results than a "purchased" list.
As well as a good list, the message must be a good one – therefore selection of a good template with a non-confusing and interesting message is paramount. Choice of title is important too, because some SPAM filters automatically put title with, for example, the word “offer” into the spam box. Good email marketing systems will invariable have a method of testing the spam function before sending.
Then it is a case of deliverability; good systems will always prevail over weaker systems because they will have a higher level of deliverability.
When, delivered, attention must be paid to the statistics and measure the campaign.