Make PL/pgSQL function feed back identity for mailboxes/relocated when there are catchall destinations. Without catchall aliases, if no virtual_alias matches, the query can just return NULL and Postfix will later check mailboxes/relocated for the address to rewrite. However, since virtual aliases are handled long before mailboxes/relocated, a catchall alias would also catch mail to mailboxes and relocated addresses, which we do not want. The way to tell postfix to keep delivering is for the virtual alias map to return the search key itself (identity function). This patch changes the postfix_virtual_alias_maps Pl/pgSQL function to do exactly that, but only if there are catchall destinations defined for the domain in question — otherwise it returns NULL when no match is found.

# All parameters are described in pgsql_table(5) / PGSQL PARAMETERS
#
# The hosts that Postfix will try to connect to and query from.
hosts = localhost

# The user name and password to log into the pgsql server.
user = postfix
password = some_password

# The database name on the servers.
dbname = mailsys

# The SQL query template used to search the database
query = SELECT uid FROM postfix_virtual_uid_map('%u', '%d')