Extract the domains from your list and verify they have valid MX (Mail Exchange) records. You can do this with a free Python script that reads your TXT file line by line.
Correct:
user1@site.com
user2@site.com
user3@site.com
Incorrect:
user1@site.com, user2@site.com, user3@site.com
| Mistake | Fix | |---------|-----| | No line breaks | Use double line breaks between paragraphs. | | Broken URLs | Test every link before sending. | | Missing unsubscribe | Include a clear, working opt-out. | | Too long | Keep under ~500 words if possible. | | No plain text version of HTML email | Always send a text fallback. | Email List Txt