MaxBulk Mailer has nothing to do with all that actually.
The message "553 Sorry, over your daily relay limit." is sent by your server. Please ask the server postmaster why you get this error message if they say there is no limit. The error says clearly 'daily relay limit'.
The message "553 Sorry, over your daily relay limit." is sent by your server. Please ask the server postmaster why you get this error message if they say there is no limit. The error says clearly 'daily relay limit'.