The following terms are defined in [MS-GLOS]:
Augmented Backus-Naur Form (ABNF)
NT LAN Manager (NTLM) Authentication Protocol
user principal name (UPN)
The following terms are defined in [MS-OXGLOS]:
Multipurpose Internet Mail Extensions (MIME)
The following terms are specific to this document:
POP3 response: A message that is sent by a Post Office Protocol - Version 3 (POP3) server in response to a message from a POP3 client.
MAY, SHOULD, MUST, SHOULD NOT, MUST NOT: These terms (in all caps) are used as described in [RFC2119]. All statements of optional behavior use either MAY, SHOULD, or SHOULD NOT.