Email News Campaign-Friend or Foe??

So I'm curious how many businesses use this method to stay in contact with their customers? It seems like such a neat idea...but I wonder if it's more of an infringement upon their free time? Do they look at my newsletter as a sort of spam? LOL I spend HOURS putting my newsletter together...choosing the right photos, writing up the little blurbs of interest...I know I don't like to read a lot when I get newsletters so I try not to put too much reading in there...course, I've only done TWO so far!! and I only have 18 subscribers!! LOL...so I hope to improve each one...adding techniques, and sales etc... But is it effective? What's the best way to get the word out about my art, any how? Inquiring minds REALLY want to know!-Me