I mean Sometimes users can write wrong e-mail adress and if i set option ON from admin options the mail or warn mail will dont go them..
But If I use PM for warn users its can be more easy and Sometimes users dont read their mails.. so If i use PM for this it would be more easy for me and for my users :-)
Yes, bad email addresses are a problem. But, I attack the problem from the opposite direction. If a member has an email rejected, THEN I send them a PM and warn them to correct their email address...
This may also keep from building up a huge backlog of unread PMs in the system. Even by doing that, I now have about 1765 PMs in mine, for example, and 394 of them are unread....