- Implement tests for counting emails in single and multiple folders, including handling of empty folders and error scenarios in `test_count_imap_emails.py`.
- Create tests for environment variable verification, IMAP connection handling, folder normalization, MIME header decoding, and message details extraction in `test_imap_common.py`.
- Develop tests for email migration, including duplicate detection, deletion from source after migration, folder creation on destination, and handling of multiple folders in `test_migrate_imap_emails.py`.
- Introduce a mock IMAP server to facilitate testing of IMAP functionalities in `tools/mock_imap_server.py`.