Mail User Agents
User Agents are
the interface software which help a user in accessing the mail service
effectively. These may be :
Remote Mail User Agent :
The most common mode of
accessing a mail server is using a Windows based client machine through IP
based connectivity, over dial-up or dedicated link. These Mail User Agents are
an integral part of the Windows software (no additional software is required)
although other mail client software may also be used. These are configured to
make a connection and valid login to the mail server and automatically send or
receive messages. Composition, reading and filing of messages are all taken
care of, at the user's end. Thus minimum connect time is used on the mail
server.Remote Mail User Agent :
For Windows95 and above, the POP/IMAP client software is supported in mail user agents such as Microsoft Exchange client, Netscape mail agent, Eudora etc. Similarly, Enterprise mail software etc. use the P7 protocol at the client end. For a DOS-based client machine, the PCBOX User Agent is available to access the mail server.
Local
Mail User Agent : Here the client logs onto the mail
server and accesses the Local Mail User Agent (e.g. Pine, mailx etc.) running
on the mail server. This may be accessed using a terminal emulation software
through a dial-up or a dedicated link.
To facilitate the usage, local Mail User Agents such as Pine support Z-modem protocol for file-transfer. At the client end, higher versions of terminal emulation software such as PCPLUS, PROCOMM etc. for DOS, and NIC¹s Zetlink and Radix for Unix/XENIX support this protocol.This enables the transfer of files onto the server for attaching into a mail to be composed. Pine also provides a search facility, to look for and obtain a particular recipient¹s e-mail address in the X.500 based NIC directory.
These users occupy valuable disk space at the server since all mails lie on the server and may also be using a long duration of connect time if they compose their mails while being logged onto the server.
The selection of the type of mail user agent for the users depends upon their connectivity to the network and the resources available with them.
X.400
Mail based NICMAIL400 service: This service is conformant
to the X.400 ITU-T recommendations. It provides the facility to handle data,
voice, image and fax. A gateway is provided to transport messages between a
SMTP/UUCP server and the X.400-based NICMAIL400 server in a seamless manner.
The NICNET mail servers are distributed at the various NITPU and State Centres, besides the Headquarters. This enhances the balance of E-mail load on the network.The User also experiences a good response since the network delay is minimal. These servers are interconnected to be
To facilitate the usage, local Mail User Agents such as Pine support Z-modem protocol for file-transfer. At the client end, higher versions of terminal emulation software such as PCPLUS, PROCOMM etc. for DOS, and NIC¹s Zetlink and Radix for Unix/XENIX support this protocol.This enables the transfer of files onto the server for attaching into a mail to be composed. Pine also provides a search facility, to look for and obtain a particular recipient¹s e-mail address in the X.500 based NIC directory.
These users occupy valuable disk space at the server since all mails lie on the server and may also be using a long duration of connect time if they compose their mails while being logged onto the server.
The selection of the type of mail user agent for the users depends upon their connectivity to the network and the resources available with them.
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Mail Servers
The NICNET mail servers are systems that run specific software to provide E-Mail service. There are various standards that define how messages are exchanged between two mail servers. Mail servers may have the capability to support one or more of these standards. The different mail servers based on their standards are : Simple Mail Transfer Protocol (SMTP) : These servers use the standard TCP/IP protocol. SMTP mail
supports the transport of textual as well as MIME-formatted messages. The
SMTP mail server generally has a dedicated IP based connection to NICNET.The System running as a SMTP server is configured on the DOMAIN NAME SERVER (DNS), which may either be the primary DNS or a secondary DNS. UUCP/UUPC mail servers : These are Unix/DOS machines using the configuration of
Unix-to-Unix Copy Protocol(UUCP) on two communicating machines.Users with
accounts on one such system access e-mail service through it, which in turn
relays all the spooled user mails to the other mail server in the background
mode at specified intervals of time.UUCP is the protocol used in Unix systems and the corresponding protocol for DOS systems is UUPC. |
X.400
Mail based NICMAIL400 service: This service is conformant
to the X.400 ITU-T recommendations. It provides the facility to handle data,
voice, image and fax. A gateway is provided to transport messages between a
SMTP/UUCP server and the X.400-based NICMAIL400 server in a seamless manner.The NICNET mail servers are distributed at the various NITPU and State Centres, besides the Headquarters. This enhances the balance of E-mail load on the network.The User also experiences a good response since the network delay is minimal. These servers are interconnected to be
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