[exim] Aliases in LDAP - good idea?

Hi,

I'm currently maintaining the Exim aliases file manually even though the users are (almost) all defined in an LDAP server. I am very tempted to store the aliases in LDAP as well, since it would simplify things quite a bit.

I am just worried on what would happen should the LDAP servers are not available: would mails be rejected with a 5xx error?

Exim documentation (Chapter 9.5) seems to say that much: "Lookup functions can return temporary error codes if the lookup cannot be completed. For example, an SQL or LDAP database might be unavailable. For this reason, it is not advisable to use a lookup that might do this for critical options such as a list of local domains.


When a lookup cannot be completed in a router or transport, delivery of the message (to the relevant address) is deferred, as for any other temporary error. In other circumstances Exim may assume the lookup has failed, or may give up altogether."

So, lacking any long-term, multi-hours at least caching mechanism, is it a good idea to put aliases in LDAP? Is there a sane/safe way to do so?


Thank you!

Rigu