Comment # 7 on bug 1095144 from Peter Varkoly

(In reply to Per Jessen from comment #5)
> (In reply to Martin Willisegger from comment #4)
> > I can confirm that the error message disappears if you enter the map without
> > path.
> > 
> > virtual_mailbox_maps = mysql:mysql_virtual_mailbox_maps.cf
> > 
> > However, no error message is displayed if you specify a non-existing map
> > file - so it is possible that the maps are simply not found in this variant.
> 
> Yes, I think that is probably the explanation. 
>  
> > virtual_mailbox_maps = mysql:blablubbhaha_mysql_virtual_mailbox_maps.cf
> > 
> > does also not print out an error message, and this file is not present in
> > any path.
> 
> Also very weird.

Do not forget: In case mysql:blablubbhaha_mysql_virtual_mailbox_maps.cf
postconf -d do not read the file
/etc/postfix/blablblablubbhaha_mysql_virtual_mailbox_maps.cf. Instead of
postconf requires now the virtual_mailbox_maps mysql parameters in main.cf in
form of:
blablubbhaha_mysql_virtual_mailbox_maps.cf_hosts
blablubbhaha_mysql_virtual_mailbox_maps.cf_query
...
See man mysql_table:

OBSOLETE MAIN.CF PARAMETERS
       For compatibility with other Postfix lookup tables, MySQL parameters can
also be defined in main.cf.  In order to do that, specify as MySQL source a
name that doesn't begin with a slash or  a  dot.
       The  MySQL  parameters  will  then  be  accessible  as  the  name 
you've  given the source in its definition, an underscore, and the name of the
parameter.  For example, if the map is specified as
       "mysql:mysqlname", the parameter "hosts" would be defined in main.cf as
"mysqlname_hosts".