I need to mass email 2,000 people. How do I avoid being accused of sending

[Will]

spam and becoming blacklisted? I have a list of 2,000 emails of customers who have bought from my business and provided their email addresses in writing. I would like to email them about my new products and website. I plan to use Outlook and the mail merge feature in Word to personalize the salutations….but I have been told that by sending a big block of emails like this, I could be mistaken as a spammer and “blacklisted” (I don’t know what that means, but it doesn’t sound good). They suggested that I send out my emails in batches of 25 so this doesn’t happen. Does sending in small batches help my cause? Anything else I should consider so I don’t get labeled as a spammer?