Here are a few steps you can take to avoid having your email address or domain placed on a blacklist:

1. Use duoble opt-in for your email subscribers
2. Include and unsubscribe link
3. Clean your email lists regularly
4. Optimize your email content
5. Secure your server
6. Avoid manually entering email address into your database.
7. Use a reputable email provider that has a good track record of preventing spam and protecting its users from phishing and other scams. This can help ensure that your emails are delivered to their intended recipients and do not get flagged as spam.
8. Follow best practices for sending email, including using a clear and descriptive subject line, avoiding the use of spammy words or phrases, and only sending email to people who have explicitly opted in to receive messages from you.
9. Monitor your sending reputation and avoid sending large volumes of email to addresses that have not been verified or that have bounced in the past. This can help prevent your emails from being flagged as spam and avoid having your IP address or domain placed on a blacklist.
10. Be careful about purchasing email lists or using third-party services to send email on your behalf. These practices are often frowned upon by email providers and can increase the risk of your emails being flagged as spam or your IP address or domain being placed on a blacklist.

By following these steps and practicing good email hygiene, you can help prevent your email address or domain from being placed on a blacklist and ensure that your emails are delivered to their intended recipients.