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- Word to the Wise: Subscription BomingBombing, ESPs, and Spamhaus:
https://wordtothewise.com/2016/08/subscription-bombing-esps-spamhaus/ - Subscription Bombing: COI, CAPTCHA, and the Next Generation of Mail Bombs:
https://www.spamhaus.org/news/article/734/ - Mailing Lists -vs- Spam Lists:
https://www.spamhaus.org/whitepapers/mailinglists/ - Confirmed Opt In - A Rose by Any Name:
https://www.spamhaus.org/news/article/635 - Spamhaus Marketing FAQ:
https://www.spamhaus.org/faq/section/Marketing%20FAQs