The Linux Electronic Mail HOWTO: Mail "User Agents"

5. Mail "User Agents"

This section contains information related to "user agents", which means the software the user sees and uses. This software relies on the "transport agents" mentioned above.

5.1 Elm

Elm compiles, installs, and runs flawlessly under Linux up to and through Slackware 1.1.1 (gcc2.4.5, gcclib 4.4.4). For more information, see the elm sources and installation instructions.

The only thing to know is that Elm's Configure script incorrectly sets the "ranlib" and "stdarg" variables in config.sh. The Elm Development Team has been informed of this little problem, so please don't bother them with it (again).

(from Chip Rosenthal - chip@chinacat.unicom.com ) The easiest way to deal with this is to create a file called config.over at the top of you Elm source tree and include the line:
```
        ranlib='ranlib'
        stdarg='define'
```
Elm and filter need to be mode 2755 (group mail) with /usr/spool/mail mode 775 and group mail.

If you use a binary distribution, you'll need to create a /usr/local/lib/elm/elm.rc file to override the compiled-in hostname and domain information:

replace "subdomain.domain" with your domain name replace
"myhostname" with you un-domainized hostname replace

        #---------- /usr/local/lib/elm/elm.rc ------------------
        #
        # this is the unqualified hostname
        hostname = myhostname
        #
        # this is the local domain
        hostdomain = subdomain.domain
        #
        # this is the fully qualified hostname
        hostfullname = myhostname.subdomain.domain
        #
        #--------------------------------------------------------

One thing you want to be aware of is that if you have Elm compiled to be MIME-able, you need metamail installed and in your path or Elm will not be able to read MIME mail you've received. Metamail is available on thumper.bellcore.com and of course via "archie".

We have heard reports that gcc and gcclib newer than v2.4.5 and v4.4.4 respectively are rather strict and fail to compile Elm. Here's the scoop as reported by ccnp@unitrix.utr.ac.za (Neil Parker) who forwarded a posting by longyear@netcom.com (Al Longyear).

ELM is using internal fields in the FILE structure in an effort to bypass the standards. (The _flag, _IOERR, and _IOEOF are old fields for the pre-POSIX runtime package. While POSIX doesn't say that you can't define these fields, it does not say that you _must_. Linux does not. It does say that programs should not be written to use them, even if they are in the implementation.)
```
         where it does         if (fp->_flag & _IOERR) ...
         change it to          if (ferror(fp)) ....

         where it does         if (fp->_flag & _IOEOF) ...
         change it to          if (feof(fp)) ...

         These are the ANSI/POSIX definitions for the same function.
```
Also, there is a nice set of diffs for Elm 2.4.23 that works just fine (for me at least) located on nic.funet.fi in the file /pub/OS/Linux/kernel/src/net-source/mail/elm-2.4.24.dif that works around some Linux-isms. While just grabbing the vanilla sources and patching with these diffs works fine, I've personally had success with just setting up the config.over file mentioned above and only patching opt_utils.c and lock.c in the Elm sources. (I run kernel 1.3.33 over Slackware 2.1.0)
In the "too cool to be true" category, there is a distribution of Elm-2.4.24 that is "PGP-aware". To try it, grab the file ftp://ftp.viewlogic.com/pub/elm-2.4pl24pgp3.tar.gz, which is elm2.4.24 with PGP hooks added. You configure and build it the same way you do normal Elm, which means you probably need to add the patches mentioned above. For what it's worth, I run it here and like it a lot.
While this item is not Linux-specific, it's perceived (wrongly) to be a nagging Elm bug nevertheless. We've heard that Elm sometimes fails with a message that it's unable to malloc() some massive number of bytes. The identified workaround is to remove the post-processed global mail aliases (aliases.dir and aliases.pag).
THIS IS NOT A BUG IN ELM. It's an error in configuration of Elm by whomever you got your binary distribution of Elm from. Elm has an enhanced, and non-compatible, format for aliases. You need to ensure that the path Elm uses for aliases is different from the path sendmail/smail uses. From the volume of reports of this problem, it's apparent that at least one major distribution 'on the street' has in the past been misconfigured. The current Slackware does it correctly.

(from scot@catzen.gun.de (Scot W. Stevenson) ) The current metamail package requires csh for some of its scripts. Failure to have csh (or tcsh) will cause most interesting errors...

5.2 Mailx

Safe yourself the pain. Just go and grab the mailx kit from Slackware 2.1.0 or later, which has a nice implementation of mailx5.5. If you're into building from sources, mailx v5.5 compiles without patching under Linux if you have "pmake" installed.

If anybody is still using it, I strongly recommend removing the old "edmail" stuff from SLS1.00 and replacing it with mailx.

5.3 Other user agents

The following also are known to run under Linux. Consult "archie" for details regarding how to find them...

Pine - from the Univ. of Washington
Metamail - allows MIME support
mh - yet another way to handle mail
deliver - file/process mail based on rules
procmail - file/process mail based on rules
Majordomo - manages e-mail lists
Mserv - provide files-by-mail