`services.postfix.extraConfig` is just a string while the
`services.postfix.config` option configures the same thing but with a
typed attrset instead which is easier to manipulate and override in Nix.
- Move the "create password hash file from hashed password" behavior to
a separate variable, since having it in the default field of config
would always cause the warning to trigger
- Change type of hashedPassword to `nullOr str`
TLSv1.0 is as deprecated as the older SSL versions, and should not be
used. I've also disabled a slew of ciphers, and hopefully this will
make us less vulnerable to downgrade attacks and similar.
SNM used to define virtual_alias_maps in extraConfig which collides with
the same parameter defined by the standard services.postfix.virtual
option. This led to *lots* of warnings during postfix startup like
```
May 02 18:29:58 nun postfix/master[24758]: warning: /etc/postfix/main.cf, line 47: overriding earlier entry: virtual_alias_maps=hash:/etc/postfix/virtual
```
Refraining from overriding virtual_alias_maps has the additional
advantage that virtual aliases defined by other modules dont' stop
working with SNM.
It seemed weird to me that preStart on postfix was used to generate
files not needed directly by postfix and for the self-signed
certificate which is also needed by dovecot. nginx.service was also
used as a proxy for when ACME certificate generation was done.
So I have created mailserver-certificates.target for when certificates
are available for other services. For self-signed that means that a
new oneshot service called mailserver-selfsigned-certificate has been
run. And for ACME this means that the target
acme-selfsigned-certificates has been reached (which is when acme has
created the self-signed certificates used before the actual
certificates provided by LetsEncrypt are created). This setup has the
added bonus that if you want to run a service to provide your own
certificates you can set that to run before
mailserver-certificates.target.
DH Parameters are only needed by dovecot so generation of that file has
been moved to the dovecot2 preStart.
And lastly the only remaining reason to for dovecot to start before
postfix was that the auth and lmtp sockets where located in a directory
created by postfix. But since they could just as well be located in
/run/dovecot2 as long as postfix has access to them I have moved them
there.
In the event that your `cfg.fqdn` is the same as a domain in `cfg.domains`, you
will not be able to receive mail for users like `user1@fqdn` because postfix
will try to deliver the mail locally.
