I'm about to start sending a newsletter to quite a big amount of users (around 60k emails). They are all customised emails, in around 30 different languages, so almost every email will be different (apart from any merge tag customisation).I've seen that the recommendation for bulk emails is to use Mailchimp, while Mandrill is for transactional emails. However, looks like Mailchimp is really focused on sending the same email to huge amounts of people, while in my case, every user may have a different final email depending on the products they bought from us. That makes me think Mandrill is a better option, as I have already used Mandrill for generating on my server these emails.In my situation, these emails are sent only after the user has bought at least one of our products (some kind of an automatic opt-in, something that looks like Mailchimp don't like at all, while Mandrill tolerates it). They are kind of newsletter emails, but really focused on keeping the user's interest and suggesting other products, only based on what she has previously bought. Something inbetween marketing and transactional (transarketing?).I'm a little worried about the warnings around the automatic opt-in thing that Mailchimp raises in their blog (many times), but creating a campaign where it is almost individually segmentated doesn't make sense to me at all, and Mandrill doesn't have a double opt-in system like Mailchimp has (of course, because it's not how Mandrill should be used).So, after all this mess of thoughts, my question is, Are there any flaws on using Mandrill as bulk messaging system, or can this be used without worries of being sued/domain-banned?
Mandrill for bulk messaging
email;bulk email;mailchimp
No, in the United States and Europe, you can never use a messaging system to automatically opt-in people who haven't opted in without any worries. Yes you can do it, but not worry free.A customer making a purchase isn't enough to absolve you from having to follow laws like CAN-SPAM and Europe's E-Privacy Directive. You may be able to get away with it, if the percentage of people marking you as SPAM stays below Mandrill's allowable rate. That will be determined by your customers and if they accept the verbiage in your email and the purpose for the message. Make sure they can unsubscribe easily to reduce your exposure to spam flags.Edit: Regardless of the laws in place, the real challenge is to keep your spam rate within the parameters allowed by the different bulk email companies (mandrill, mailchimp, etc) and a good reputation with the email providers  (gmail, yahoo, aol, etc). If you fall out of favor with any of these groups then you will have a difficult time communicating with your customers via email. Mandrill works well as a bulk mail sender if you handle the emails like individual transactional emails. 