There are many places (see the Linux MAIL HOWTO in comp.answers or on rtfm.mit.edu for a list), but the definitive place is in the sendmail+IDA sources. Look in the directory <IDA_SRC_PATH>/ida/cf for the files DBM-GUIDE, OPTIONS, and Sendmail.mc.
Thanks go to Neil Rickert and Paul Pomes for lots of help over the years regarding the care and feeding of sendmail+IDA and to Rich Braun for doing the initial port of sendmail+IDA to Linux.
There is no “true standard configuration” of electronic mail transport and delivery agents and there is no “one true directory structure”.
Accordingly, it is necessary to ensure that all the various pieces of the system (Usenet news, mail, tcp/ip) agree on the location of the local mail delivery program (lmail, deliver, etc.), remote mail delivery program (rmail), and the mail transport program (sendmail or smail). Such assumptions are not generally documented, although use of the 'strings' command can help determine what files and directories are expected. The following are some problems we've seen in the past with some of the commonly available Linux binary distributions and sources.
Some versions of the NET-2 distribution of tcp/ip have services defined for a program called 'umail' rather than sendmail.
There are various ports of Elm and mailx that look for a delivery agent of /usr/bin/smail rather than sendmail.
Sendmail+IDA has a built-in local mailer for 'deliver', but expects it to be located in /bin rather than the more typical Linux location of /usr/bin.
Rather than go to the trouble of building all the mail clients from sources, we generally fake it with the appropriate soft links...
You set the default smart host via the RELAY_HOST and RELAY_MAILER parameters in the sendmail.m4 file that is processed into sendmail.cf.
To forward mail to a particular host or domain to a designated relay system, generally use the mailertable.
For example, to forward mail for relayhost.com to their uucp gateway system 'uucpgate'.
(in mailertable)UUCP-A,uucpgate relayhost.com
Frequently, Internet hosts will have trouble getting mail into misconfigured remote sites. There are several variants of this problem, but the general symptom is that mail is bounced by the remote system or never gets there at all.
These problems can put the local system administrator in a bad position because your users generally don't care that you don't personally administer every system worldwide (or know how to get the remote administrator to fix the problem). They just know that their mail didn't get through to the desired recipient on the other end and that you're a likely person to compain to.
A remote site's configuration is their problem, not yours. In all cases, be certain to NOT break your site in order to communicate with a misconfigured remote site. If you can't get in touch with the Postmaster at the remote site to get them to fix their configuration in a timely manner, you have two options.
It is generally possible to force mail into the remote system successfully, although since the remote system is misconfigured, replies on the remote end might not work...but then that's the remote administrator's problem.
You can fix the bad headers in the envelope on your outgoing messages only by putting a domaintable entry for their host/domain that results in the invalid information being corrected in mail originating from your site:
# (in domaintable) braindead_site.correct.domain.com braindead_site.wrong.domain.com
Treat them as totally brain-dead and strip off all hostname.domain information in the envelope of messages to them from your site.
The '!' in the following results in mail being delivered to their remote site and appearing to be locally originated (for sendmail purposes). The return address for your site will not be changed, so the proper return address will still show up in the message.
# (in mailertable) TCP!braindead_site.correct.domain.com braindead_site.wrong.domain.com
Regardless, even if you get mail into their system, there is no guarantee that they can reply to your message (they're broken, remember...) but then their users are yelling at their administrators rather than your users yelling at you.
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
Free to Linux Journal readers.Register Now!
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- Non-Linux FOSS: Caffeine!
- Managing Linux Using Puppet
- Doing for User Space What We Did for Kernel Space
- Parsing an RSS News Feed with a Bash Script
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- Tech Tip: Really Simple HTTP Server with Python
- Rogue Wave Software's Zend Server
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide