CAVEAT.txt

A collection and discussion of pitfalls in cmail that might
not be immediately evident.

Database schema versioning
--------------------------
The 'meta' table contains a key describing the current database
schema version. The schema is, as of currently, extremely
volatile and might change between versions, commits and without
notice. Upgrade paths will only be reliably provided between
tagged releases.

Internationalized Email
-----------------------
While cmail supports UTF8 characters in paths as well
as mail data (via SMTPUTF8/8BITMIME), RFC 6531 specifies
that the domain part may be transmitted as either
A-label (punycode) or U-label (UTF-encoded string).
Care must be taken when specifying adresses and wildcards
containing non-ASCII chracters.

Case-sensitive matching
-----------------------
Currently, all paths are matched completely case-sensitive,
including the domain parts. This may be fixed in the future.

Bounce handling
---------------
Bounces (delivery problem notifications generated for messages
within the systems responsibility) are generated upon a number
of temporary failures or one permanent failure for a mailing.
They are generated by the outbound module (cmail-dispatchd) which does,
for reasons of code duplication and separation of concerns, not
currently have code paths for routing mail locally.
Bounces destined for addresses that are local will still be routed
outbound and will be delivered by the normal SMTP client delivery
method. This implies that in order to receive bounces locally,
cmail-dispatchd must be able to resolve your domain to the local server,
preferrably via MX records and that cmail-smtpd must be accepting incoming
mail for these adresses. This should be standard in most setups,
yet it might still be good to know. There are currently no plans
to change this behaviour.