Here are some things to do and not do: - Send only to real subscribers. Duh. Notice that I didn't say "send only to my random email address list I got from my old pal Salvatore Testosteroney Degongio". Sorry, it doesn't work that way. - Unexpected content. If your subscribers aren't getting the content they expect and at the frequency they expect, they stop engaging, they get mad, they pout, then they click the Report Spam button. - Send only to valid email addresses. Um, it'd be a good idea for you to not send email to the same bunch of broken email addresses repeatedly. Scan your list to make sure there aren't misspelled domains in there like @ggmail.com, @hotmaidl.com, or @IcantSpell.net. These should be removed automatically by a good email service provider. Get the full story at Social Media Today