On 4/2/20 8:18 AM, Grant Edwards wrote:
Then DO NOT use sendmail. Sendmail is only for the ultra-professional who already knows how to configure it (not joking).
I take exception to that for multiple reasons: 1) Bootstrapping - you can't learn something without actually using it.2) I've been quite happily using Sendmail on multiple platforms for 20 years. 3) Sendmail is capable of working in every single email scenario that I've seen in said 20 years. The same can't be said for other MTAs.
If all your mail gets sent via a single SMTP server at your ISP (or wherever), then Sendmail is definitely not what you want.
That depends.If you have a fleet of Sendmail servers, chances are good that you will prefer to re-use the same solution, even in small / simple role. Read: The Devil that you know.
If you don't need local queueing (so you can send email while offline), then I'd pick ssmtp.
(20)ProTip: You really do want local outbound queueing /somewhere/ on box.You don't want your web application to error out when it can't reach it's SMTP server. You don't want t loose that receipt for the transaction that the customer just made. Can you regenerate the receipt? ;-)
You can have each application do it's own queuing / re-sending, r you can rely on the local MTA to do it for you.
Where do you want the queuing complexity? A local queuing MTA is simple and solves a LOT of problems.
If you want something even more sophisticated (e.g. something that can deliver mail locally and receive inbound mail using SMTP), then postfix or exim would probably the be the next step up:
I would add Sendmail to the front of that list. But I might be biased.
I've read claims that there are things you can do with sendmail that Exim or Postfix can't handle, but I'm not sure I believe it. I am sure I'll never need to do any of those things.
I don't know Exim or Posfix well enough to comment with any authority.I do know that I Sendmail, Postifx, and Exim all handle (E)SMTP without any problem.
I think that Postfix can be made to handle UUCP. Sendmail has four different ways that it can use UUCP, built in. I have no idea about Exim.
Sendmail can easily work with other protocols, Mail11, fax, pager, news gateway (send and / or receive). It's also easy to add additional protocols without needing to recompile anything, only configuration changes are needed.
I don't know where in the list I lost Postfix and / or Exim, but I expect that they didn't make it through the last paragraph.
For a long time, Sendmail did have one claim to fame that no other MTA had. Specifically Sendmail had the ability to use milters (mail filters) and filter email during the SMTP transaction. It's trivial to hook ClamAV, SpamAssassin, and just about anything you want into checking mail during the SMTP transaction such that you have the ability to reject, not bounce, the message. Thus making the sending host be responsible for it.
I'm sure there are many more and far more esoteric things that Sendmail can do. Though I doubt that many of them are as germane today as they were in the mid '90s. I was recently playing with the ability to have a domain spread across multiple servers and configuring Sendmail to route messages to the proper back end server, a feature known as LDAP routing.
Yes, Sendmail has a lot of power, much like unix. It will happily hand you a loaded gun, encourage you to point it at your feet and empty the magazine as fast as possible. When you're done, it will help you reload and do it again.
If you know how to wield this power Sendmail can be a wonderful tool that can be used in all of the scenarios described in this thread. It's also relatively trivial to have Sendmail be a basic queuing outbound only MTA that uses ISP smart hosts to provide SMTP services to local applications.
But I really object to the "ultra-professional" comment, because everybody has to start somewhere.
-- Grant. . . . unix || die
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