The system receives a message from a user, along with a recipient list and generated personalized messages for recipients of the recipient list. The system determines the format of the message, and whether to, and how to, modify the message based on information about the recipient. For example, a recipient category may be used to determine how to personalize a message for each recipient. A relationship between a sender and recipient may be determined using, for example, a database of relationship information. The system modifies, for example, text, images, or video of the message to generate the personalized message. The system may access historical communications records such as a chat group record, a contacts list, a text message record, an email message record, a social media post record, or a comments record corresponding to a media content item to determine how to personalize a message.