fixes #414

Update README.md

Added latest front page appearance of Mail-In-A-Box to README.md

Echange -> Exchange

Closes #413.

security.md: add links to appropriate source files in various places to make it easier to inspect the code to verify the statements; unfortunately line numbers will drift but it would be nice if we could link right to line numbers

after installing an SSL certificate from the control panel the page wasn't being refreshed, broken in ec73c171

Make SPF forbid any outbound mail from non-mail domains

Improve DMARC and SPF record descriptions

Unfortunately our users/aliases database is case sensitive. (Perhaps I should have defined the columns with COLLATE NOCASE, see https://www.sqlite.org/datatype3.html.) Postfix always queries the tables in lowecase, so mail delivery would fail if a user or alias were defined with any capital letters. It would have also been possible to add multiple euqivalent addresses into the database with different case.

This commit rejects new mail users that have capital letters and forces new aliases to lowecase. I prefer to reject rather than casefold user accounts so that the login credentials the user gave are exactly what goes into the database.

https://discourse.mailinabox.email/t/recipient-address-rejected-user-unknown-in-virtual-mailbox-table/512/4

Use lowercase h for consistency in aliases template - it reads better…

This also includes fixes for a typo and some whitespace inconsistencies in
mailconfig.py. In fact the capitalisation change and those fixes are the
remnants of a patch I had been running that changed the default aliases - it
was through developing it that I found the issues.

(I wanted to bring the number of patches I apply before deploying to zero and
in the case of this one I've come to view the way MIAB already is as superior,
so I've undone the core of my patch and these tiny issues are all that remain).

A lot of legit mail servers try again between 200 and 285 seconds, then
3 hours later. Why? RFC is not strict about retry timer so postfix and
other MTA have their own intervals. To fix the problem of receiving
these e-mail really latter, I reduced the delay of postgrey to
180 seconds (default is 300 seconds).

Fixing minor misspelling of the word: encrypted

The submission port began offering SSLv3.

With `encrypt`, the smtpd_tls_protocols option is ignored and smtpd_tls_mandatory_protocols must be set instead.

see e39b777a

Starting with my dnswl.org modifications to postgrey.

The OVH VPS provider creates systems without /dev/stdout. I have never seen that before. But fine. We were passing it as a command line option to `openssl req`, but outputting to stdout is the default so it's not necessary to specify /dev/stdout.

Fixes #277. Also https://discourse.mailinabox.email/t/500-internal-server-error/475/10.

if the main ssl cert is expiring soon, the end of setup would display the control panel instructions as if the cert were self-signed