What does the message below mean and how can I fix it? It's happens every night and is causing the e-mail to bounce and create a new ticket everyday around midnight.

Got a packet bigger than 'max_allowed_packet', SQL: 'INSERT INTO article_plain (article_id, body, create_time, create_by, change_time, change_by) VALUES (2591, 'From EPonomarenko@sandcherry.com Thu Sep 2 15:05:02 2004