The most commonly recommended hashing algorithms in email marketing include: - SHA-256: Part of the Secure Hash Algorithm (SHA) family, SHA-256 provides a good balance between security and performance. - Bcrypt: Known for its adaptability, Bcrypt incorporates a salt to protect against rainbow table attacks and allows for tuning its computational cost. - Argon2: Winner of the Password Hashing Competition (PHC), Argon2 is designed to be resistant to both GPU and ASIC attacks.