TORONTO USERS GROUP for Midrange Systems
TUG eServer magazine July 1996: Volume 11, Number 6

E-MAIL Unleashed -

OS/400 POP and MIME Support

By Evelyn Porter

The World Wide Web may be the fanciest part of the Internet; newsgroups may be the most controversial; and search engines may be the hottest stocks around, but when it comes to making the Internet truly useful you can't beat electronic mail. While OS/400 has had an SMTP gateway for some time, the newly announced Version 3 Release 2/7 has enhanced e-mail capability with a POP3 server and support for the MIME extensions.

POP stands for Post Office Protocol. The idea behind POP is simply disconnected mail. If you only connect to the network every once in a while, you need a place to store your mail until you can pick it up. The POP server provides that mailbox function. It stores the mail until you connect, then downloads all your mail to your client machine. All of the mail processing, such as reading, filing, replying, and so on, are performed on your client system.

One of the advantages of using POP for mail distribution is the availability of POP clients. There is POP client code for UNIX systems, Macintosh, OS/2, DOS and Windows. This means that you can offer your users an e-mail system that continues to use the AS/400 server that you've got in the office already, with its reliability and ease of management, but with a client like Eudora or any of the other popular POP clients.

How does this work? The POP server is a store-and-forward mail system that provides electronic mailboxes on the AS/400 from which a POP client can retrieve mail. It uses the AnyMail/400 mail server framework along with the system distribution directory to process and distribute e-mail. It uses the simple mail transfer protocol (SMTP) to forward mail. The POP server is only a temporary holding area for mail. Once the client has connected and retrieved its mail, the POP server deletes those messages.

When using OV/400 to send mail, you need a directory entry for every user to whom you want to send mail, as well as one for every user who wishes to receive mail. This all right as long as you only want to communicate with people within your own organization because it is possible to keep track of all your own users. You need to do this anyway, because you probably want to manage their access to applications on your system. However, when you want to communicate with the rest of the world, this requirement becomes a management headache. A POP client, on the other hand, using SMTP can send mail to any remote SMTP user without having a directory entry for each user. With V3R2(CISC) & V3R7(RISC), you can tell OS/400 to use SMTP instead of SNADS to deliver the mail by changing two new parameters: the Mail Service Level and Preferred Address.

Another new function of V3R2/7 is something called MIME. MIME stands for Multi-purpose Internet Mail Extensions, but for most people, it means the ability to attach binary objects like video, image, audio or files like spreadsheets and word processing documents to your mail message. The POP server can figure out what to do with the attachment, so your POP clients will receive their MIME attachments just fine. What about your OV/400 users?

AnyMail/400 server framework steps in again to handle this. A MIME conversion function converts any MIME text attachments into an OV/400 note and converts any binary attachments into documents with a type of "IBM Personal Computer File". References to the attachments are placed in the OV/400 note, so that the recipient can tell that there are some binary files to look for.

With V3R2 & V3R7, the POP server and MIME support have greatly extended the E-mail capability of OS/400. It may not be glamorous, it may not be controversial, and it probably won't make the front cover of Infobabble Weekly, but true to the design of the AS/400, it sure is useful. T < G