I did my first newsletter mailing today to the 6,000 members who opted in over the last year to WalkJogRun for infrequent email updates and I've got to tell you - it was a blast! I wrote the content and Jeff put together a design for the format, correcting a few things here and there. We used Campaign Monitor to send the messages and the tools are perfect. I uploaded a CSV list from my database of the opt-in members while Jeff uploaded the HTML and ran a few tests to make sure his semantic markup looked good in a range of email clients. They currently charge $5 base cost plus one cent per email so it cost us just over $65 for the list. At 1pm CST 6,000 WalkJogRun members emails were on their way and we had 5 mins to wait before the stats started to come in.
The first response of course is all the bounces from mail servers around the world declaring hard and soft bounces for their domains. Next was a swarm of Out of Office replies in the reply to email address box. Some of these were "I'll be out of the office until..." but some were "I'll be out of the office - forever! I no longer work at ...". Some of these were really funny to read, others straightforward. Being obsessive about things like this, every 15 minutes I would hit refresh to see the open rate and clickthrough rate climbing. As it stands at 2pm (26 hours into the mailing) there have been 1,729 unique opens and a 486 clickthroughs to the site or the articles, 34 people have unsubscribed and 176 emails bounced (101 hard). The reports give you a great overview of the campaign progress to date and allow you to drill down to view opens over time, unsubscribes over time, link activity and plenty more.
My only concern is that we are 30% deep into the open rate with 0.26% spam reports. On further investigation, all but one of the spam reports are from hotmail accounts. I'm very familiar with their process for spam having witnessed my wife innocently configuring her email. I'm not sure if it's a default setup but her email is set to only receive mail from people in her address book. All other mail goes to the spam trap. Every few days she looks in the spam trap and reads messages in place, transfers some to her inbox and just outright deletes others. The majority of these are offers from companies she gave permission to keep in touch with her. She doesn't think of it as spam and the separate bucket is just a convention to her for reviewing offers. I believe she, and many other hotmail users are inadvertently flagging marketing messages they opted-in for as spam, but not appreciating the way hotmail treats these reports. Campaign monitor has a 0.25% tolerance for spam at which point they will terminate your account according to the guidelines so I emailed them to let them know that there is a disturbing trend that of the 15 spam complaints, all but 1 was a hotmail account. My theory is that there is something other than a deliberate spam report decision being made. Fortunately the campaign monitor guys are Australian so it was 1pm their time when I sent my message at 11pm from Chicago last night. Within minutes I had a hand crafted response thanking me for my attention to spam and letting me know that I should be in touch again if it continues to rise. I just emailed Matthew with a note to say that we are considering a double opt-in procedure and a note to say "please add adam@w... to your address book" so hopefully that will cool the waters. I'm also sure that this is just teething trouble for our first mailing and subsequent emails will run more smoothly.
If I could do it all over again I would have used the database to categorize the members by membership duration to see if there is a pattern in unsubscribes or spam reports since it is over a year since people opted in. I'm going to speak to the Campaign monitor guys to see if there is a way to update my list with categories after the fact for this purpose. We have another 5,000 members in our database who opted out who will never receive a message from us and lastly 5,000 members who joined before we added the opt-in box. For this last group, we're going to add a yes no question next time they visit the site to see if they want to opt-in. This should make sure we keep growing the list without irritating people!

Thanks for the kind words. Just to clarify, just emptying your spam folder with an email in it is not enough to trigger a spam complaint in Campaign Monitor. There needs to be an manual pressing of the 'junk' button before it shows up as a complaint.
We also do send warning emails before any action is taken, and will review individual cases. As long as you are following best practices, you should be fine!