We did notice that in your most recent email you specified that you are attempting to send messages to 5,000 members. Please note that your shared hosting account is only allowed to send 1,000 email messages per day. If you are attempting to send messages to all 5,000 members at once, then this may be the cause of your error. Unfortunately this limit cannot be increased beyond the 1,000 messages currently allowed. The only suggestion that we could make is to either use a third party mail service for sending notifications, or to migrate your forum to a virtual dedicated or dedicated hosting solution, which starts at 1,000 relays per day but this limit can be increased.