[BlueOnyx:26347] Re: 5210R sendmail to postfix switch questions

[oldcabin webmaster]

Thank you

On Mon, Jul 3, 2023, 3:41 PM Michael Stauber via Blueonyx <
blueonyx at mail.blueonyx.it> wrote:

> Hi Tim,
>
> > 5210R
> >
> > I am pondering switching from sendmail to postfix.
> >
> > Anything that I should be aware of with regard to what is going to
> > change regarding my client's email client setups?
> >
> > Is there anything that they will have to change in their settings?
> >
> > Can I switch back if I suddenly run into issues (my clients)
>
> On 5210R/5211R you can switch between Sendmail and Postfix at any time
> and in either direction. Typically the clients won't even notice and no
> config changes are required server side or client side.
>
> The main difference between Sendmail and Postfix (as far as BlueOnyx
> goes) is this:
>
> Postfix supports SNI. So it will make use of *all* SSL certificates.
> That includes the GUI's cert and the SSL cert of all Vsites that have
> SSL enabled.
>
> Whereas Sendmail could only use a single SSL certificate and therefore
> only used the GUI's SSL cert.
>
> With Postfix your clients (who have SSL enabled on their Vsite) no
> longer get an SSL certificate mismatch if they use SMTPS, POPS or IMAPS
> and their configured mail-endpoint on the BlueOnyx is the domain name of
> their Vsite.
>
> Of course: If you ever have clients who use *that* setup and switch back
> from Postfix to Sendmail? Yeah, then they get the "certificate mismatch"
> again, because Sendmail only uses the GUI cert, which doesn't have
> provisions for any Vsite SSL.
>
> Other than that? Postfix is more robust and takes abuse a lot better
> than Sendmail. The way we have Postfix set up on BlueOnyx is that each
> time when Postfix is started it parses the Sendmail configuration and
> creates a new Postfix configuration on the fly. That way the
> configuration of both MTAs remains identical and "doesn't drift apart".
>
> Should you ever wish to configure Postfix differently than the GUI
> allows, or want to set a parameter that the GUI doesn't have for the
> Postfix configuration? You can put your changes into this script, which
> will never be overwritten by YUM updates:
>
> /usr/sausalito/bin/custom-postfix-confgen.sh
>
> There is an example in that file that shows how it's done. This script
> runs at the end of the auto-configure of Postfix that happens during
> each Postfix restart. So you have full flexibility of how you want to
> configure that service if you want to tweak it further than the GUI allows.
>
> Let me know if you have any further questions and I'd be glad to help.
>
> --
> With best regards
>
> Michael Stauber
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>
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