Technical data

Mail Services

Mail Services are an extremely important part of TCP/IP Services. Everyone who

uses the network — from administrators, to programmers, to users accesses —

this service on a regular basis. This chapter describes Post Office Protocol (POP),

SMTP, and IMAP.

Things to Consider

In planning your TCP/IP Services for OpenVMS mail services, consider the

following:

• Should I use POP or IMAP for my mail services?

• Can my SMTP clients and servers communicate?

• Will OpenVMS mail headers be translated by the chosen protocol?

• What types of mail clients will I support?

• What types and sizes of files will the mail system encounter?

6.1 Post Office Protocol (POP)

The Compaq TCP/IP Services for OpenVMS Post Office Protocol (POP) server

and the SMTP server work together to provide a reliable mail service. POP is

a mail repository used primarily by PCs to ensure that mail is accepted even

when the PC is turned off. With POP, the PC user need not be concerned with

configuring the system as an SMTP server. The user logs on to the client system’s

mail application, and the POP server forwards any new mail messages from

the OpenVMS NEWMAIL folder to the PC. The POP server is an OpenVMS

implementation of the Post Office Protocol, Version 3 (RFC 1725) and is based on

the Indiana University POP server (IUPOP3).

The POP server is assigned port 110, and all POP client connections are made to

this port.

6.1.1 POP Server Process

The POP server is installed with SYSPRV and BYPASS privileges and runs in the

TCPIP$POP account, which receives the correct quotas from the TCPIP$CONFIG

procedure. The POP server is invoked by the auxiliary server.

TCP/IP Services implements the UNIX internet daemon

inetd

function, through

the security and event logging of the auxiliary server process. The auxiliary server

simplifies application writing and manages overhead by reducing simultaneous

server processes on the system. In addition, the auxiliary server does the following:

• Eliminates high overhead resulting from nonstop running of all service

processes.

• Uses proxy and service databases to provide system security through

authentication of service requests.

• Supports event and error logging.

Mail Services 6–1