On Friday, April 3, 2020 6:23 AM, Grant Edwards <grant.b.edwa...@gmail.com> wrote:
> On 2020-04-03, Caveman Al Toraboran toraboracave...@protonmail.com wrote: > > > though i'm a bit curious about sendmail (if your > > time allows). do you mean the ebuild "sendmail"? > > Yes. I meant the program provided by the "sendmail" ebuild. That is > the MTA named "sendmail" that's been around since the universe cooled > enough to form atoms: > > https://en.wikipedia.org/wiki/Sendmail > > For many years it was the de-facto standard MTA for Unix systems. > > It's very powerful but the configuration file format is almost > impossible to understand, so people developed an m4 application that > accepted a slightly less cryptic language and generated the sendmail > configuration file. At it's peak back in the early 90's there were > approximately five people in the world who actually understood > sendmail, and none of them ever worked where you did. The rest of us > stumbled in the dark using the finely honed cargo-cult practices > cutting and pasting random snippets out of example configurations to > see what happened. Usually what happed is that mail was lost or flew > around in a loop multiplying to the point where a disk parition filled > up. > > That said, sendmail has features that no other MTA has. For example, > it can transfer mail using all sorts of different protocols that > nobody uses these days. > > Back in the 90's a number of replacement MTAs were developed such as > qmail, postfix, exim, etc. When you installed one of these, (instead > of the classic sendmail), they would usually provide an executable > file named "sendmail" that accepted the same command line arguments > and input format that the original did. That allowed applications who > wanted to send email to remain ignorant about exactly what MTA was > installed. > > Exim, postfix, qmail and the others were all still full-function MTAs > intended for a multi-users system. They could route mail to different > destinations (including delivering it locally to a variety of mailbox > types) and accept inbound email from other MTAs. While they were far > easier to set up and maintain than the original sendmail, they were > still massive overkill for a computer that was used only by a single > person where reading mail was done via POP/IMAP and all outbound mail > was handed over to a single outside mail relay. They often didn't > deal well with the fact that they were running on a host that didn't > have a "real" hostname that meant anything to the outside world, and > that the local hostname had nothing to do with the email addresses of > the user(s). > > For that use case, simple MTAs like msmtp, ssmtp, and nullmailer were > written that don't handle incoming mail at all, and where all outbound > mail is sent to a single mail relay host. The first two don't even do > any queuing: if you try to send mail when your relay host is > unreachable, then the send simply fails. > > These too, when installed, provide an executable named "sendmail" that > accepts the same command line options and input format as the original. wow, didn't know sendmail's syntax was so hard it needed a compiler :D thank you very much for your help. highly appreciated. rgrds, cm
