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