dovecot - Nov 2012 - Maildir conversion

Hi all,

I am using Dovecot 1.2.7, and trying to do my first Mbox to Maildir 
conversion. So I created a small script:
> #!/bin/bash
>
> ls > userlist.txt
>
> for i in `cat userlist.txt`; do
>         echo "---------------------";
>         echo "Converting user $i...";
>         echo "---------------------";
>
>         su - $i -s /bin/bash -c "/opt/scripts/mb2md.pl -s mail
-R";
>         su - $i -s /bin/bash -c "/opt/scripts/mb2md.pl -m -s 
> /var/mail/$i";
>         su - $i -s /bin/bash -c "cp ~$i/mail/.subscriptions 
> ~$i/Maildir/subscriptions";
> done
>
> rm -f userlist.txt
I would like some help with the following:

1. Trying it, I get multiple warnings for some mailboxes like
this:
> "WARNING: UID from X-UID: header too low. Ignoring it
Is this a problem? Or I can ignore it?

2. I understand that I also have to instruct my MDA (procmail) to 
deliver mail to the new location. I found that I have to create an 
/etc/procmailrc with the following line:
> DEFAULT=$HOME/Maildir/
My question is: Some users have their own .procmailrc file inside their 
home directory, to filter mail etc. Their file does not contain the 
above statement. Would the default procmailrc file be processed for them 
as well? Or their file takes precedence, causing the default file not to 
be processed at all?

Thank you

<snip>
> 
> 2. I understand that I also have to instruct my MDA (procmail) to deliver
mail
> to the new location. I found that I have to create an /etc/procmailrc with
the
> following line:
> 
>> DEFAULT=$HOME/Maildir/
> 
> My question is: Some users have their own .procmailrc file inside their
home
> directory, to filter mail etc. Their file does not contain the above
> statement. Would the default procmailrc file be processed for them as well?
Or
> their file takes precedence, causing the default file not to be processed
at all?
> 
> Thank you
> 
> 
On my systems it works that way. Only the /etc/procmailrc file has that
statement.