201- [ ] Tests fail when your new logic is broken
202- [ ] Happy path is covered
203▶- [ ] Edge cases and error conditions are tested
204- [ ] Use fixtures/mocks for external dependencies
205- [ ] Tests are deterministic (no flaky tests)
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209
210- No `eval()`, `exec()`, or `pickle` on user-controlled input
211▶- Proper exception handling (no bare `except:`) and use a `msg` variable for error messages
212- Remove unreachable/commented code before committing
213- Race conditions or resource leaks (file handles, sockets, threads).
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233
234 Raises:
235▶ InvalidEmailError: If the email address format is invalid.
236 SMTPConnectionError: If unable to connect to email server.
237 """
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236▶ SMTPConnectionError: If unable to connect to email server.
237 """
238```