We are often advised to build large email lists of people who are relevant to the books we write. It follows that all of us are on such lists whether we care or not. Do you read emails that essentially "sell" a book that's in sync with your interests/profession? If most people don't, then simply having a list is of dubious value, unless more layers of action are useful.
I did a reading once with a guy that pulled my contact info from the emails we exchanged with the emcee and pasted them onto his books' email lists. I don't read the emails anymore, they immediately go in the trash bin.
I honestly don't read them & because I don't---I feel a little strange sending people emails advertising my book.
Depends, if it is an opt in list or a list of contacts in the profession then it can be of immense value. Getting your new title seen by "interested parties" (retailers, media, TV/Radio, magazines, newspapers, reviewers, libraries, colleges, etc) as well as potential buyers, can go along way to giving your book launch a huge boost. It is not easy building this kind of list, you can collect/build it as you go along, or you can out-source the task to a publicist for example, as part of your marketing campaign.
Jeff, since I am a retired lady who will be 70 on November 5th, I have the time to subscribe to many websites and blogs pertaining to writing and books. I see many books in sidebars being promoted by website designers and blog authors. This helps reinforce in my mind that my retirement project is quite unique. I, too, have a book in the making.
I do if they come on my desktop, but if they ding my phone - no. I think the setting has to be right for me to take a look.