mail_addr field [split from (HowTo) Replace courier with dovecot]

[joximu]

hm, ok. This script won't break any installation (but the other enhancement scripts which need the field, maybe will :-). The update script just needs to fill in the complete mail address for all records where it's missing...

And hey: it's svn - so people should have a look about it. For the RC4 of course we need the update part.

Question we should maybe discuss: as a first start, we only fill the field for the real mail boxes - right? In a second step, we maybe could use it also for the forwardings - but this is far less important...

/J

PS: I did comment the 6 lines... of course (just took some old code out so it will be cleaned)