[FIX] Guard against "Invalid address format" error thrown by mailer libs when sender_email pref is not set.
[FIX] Guard against "Invalid address format" error thrown by mailer libs when sender_email pref is not set.


git-svn-id: a7fabbc6a7c54ea5c67cbd16bd322330fd10cc35@57302 b456876b-0849-0410-b77d-98878d47e9d5

oregional/tiki,tikiorg/tiki,oregional/tiki,oregional/tiki,tikiorg/tiki,tikiorg/tiki,oregional/tiki,tikiorg/tiki