Why is SMTP port 25 blocked?

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Tags

1. #computer
2. #thousands
3. #reason
4. #restrict
5. #millions
6. #writers
7. #broadband
8. #infected
9. #default
10. #hijacked
11. #because
12. #prevent
13. #connections
14. #block
15. #virus
16. #emails
17. #providers
18. #cable