Email newsletters are easy until you want to self-host and between Gmail, live, etc only 2/3 of providers will receive your messages at all and this one guy uses a corporate email address for everything for some reason and their antivirus blocks half the messages you send out despite none of them having attachments or suspicious links, even the ones that have no links at all. Then someone finds your personal email address to tell you that every time they try to confirm their email address by sending back the broken string, your server refuses the connection, so they can't even with up, and they've been trying for months. Meanwhile, someone's spamming people with fake emails sent (spoofed) from your server and opf rules are causing a transactional email sent to your own inbox for every rejected email, and you've given up on trying to respond to any real messages because you just can't find them.