You are the Network Administrator for a company that frequently exchanges confidential emails without outside parties (clients, vendors, etc.). You want those emails to be encrypted; however, you want

DES is a symmetric algorithm requiring both parties to first securely exchange an identical secret key, introducing key distribution complexity before any encrypted email can be sent.

MD5 is a one-way cryptographic hash function used for integrity checking, not for encrypting or decrypting message content.

Asymmetric encryption uses a public-private key pair where the sender encrypts a message using the recipient's freely distributed public key, removing the need for a secure out-of-band key exchange before communication begins. This is the foundation of email encryption standards like S/MIME and PGP, and it is precisely this property - no secret key distribution problem - that makes it the lowest-friction approach. The recipient then decrypts with their private key, which never needs to be shared.

Symmetric encryption requires a shared secret key to be securely distributed to every communication partner in advance, which is operationally difficult especially when communicating with external parties.