Re: [exim] Exim 5 Wishlist

Marc Perkel wrote:
> One thing I'd like to see in Exim 5 is an all SQL version where mail is
> stored as SQL and there's really tight SQL support.
>

100% do-able as-is.

Modify all routers and transports, write most of their functionality into acl's.

Most 'work', including verify = recipient equivalent, needs to be done in the
appropriate acl_smtp_<whatever> and be completed no later than acl_smtp_data.

That (may) include the 'local delivery' - i.e. done before reaching conventional
router/transport sets.

There is not necessarily a conventional queue, so retry is also up to triggers /
stored procedures et al against info in the DB, ELSE SQL cron scripts.

DNS, routing decisions and such can become a RBK, and I haven't bothered to look
at what would be needed for non-smtp traffic. Simply did not allow any on the
test rig, as even its MLM (Ecartis) does an IP-based smtp session.

CAVEATS:

- Getting POP/IMAP integration working can spoil your day.

- Parlour trick.

- Not really worth it. Seriously.

- Better off hacking PowerMail or DBMail if SQL is your fixation.

- For MTA's, SQL is handy for lookups, but about as far from a panacea as you
can get for general storage. Note that even those MTA that DO use SQL may use it
only to 'index' messages stored in the fs, not in the DB itself.

Note the scarcity of use of the current 'bespoke' SQL-based MTA's, and figure
there are planty of reasons - and of very long-standing - for that.

Among them that Exim, with near-as-dammit *ANY* fs for storage works better and
faster as-designed than they do anyway. And with fewer failure modes.

JM2CW, but BTDTGTTS

Bill Hacker