[exim] How to add item to whitelist stored in LDAP every tim…

Hi All!

The task is to append item to the whitelist of addresses every time a
local user sends an email out.
The whitelist is stored in LDAP. I wrote a perl script for writing
e-mail to properly branch of LDAP tree.
How to run a script when a local user sends a message out ?

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Thank,
Oleg O. Orlov