An electronic device comprising: a communication interface; a display; memory storing instructions; and at least one processor configured to execute the stored instructions to: control the display to display a message including a plurality of multi-byte Unicode contents corresponding to user inputs, receive a request for transmission of the message, based on the request, identify that the message corresponds to a multipage message requiring transmission of a plurality of pages including a first page and a second page, if a first portion of one of the multi-byte Unicode contents is provided at an ending portion of the first page and a second portion of the one of the multi-byte Unicode contents is provided at a starting portion of the second page, modify the multipage message by moving the first portion included in the ending portion of the first page to the starting portion of the second page, and control the communication interface to transmit the modified multipage message including the first page and the second page, wherein the first portion and the second portion independently constitute undefined data as defined by Unicode and, when combined in the modified multipage message, the first portion and the second portion are recognizable as defined data as defined by Unicode. a communication interface; a display; memory storing instructions; and at least one processor configured to execute the stored instructions to: control the display to display a message including a plurality of multi-byte Unicode contents corresponding to user inputs, receive a request for transmission of the message, based on the request, identify that the message corresponds to a multipage message requiring transmission of a plurality of pages including a first page and a second page, if a first portion of one of the multi-byte Unicode contents is provided at an ending portion of the first page and a second portion of the one of the multi-byte Unicode contents is provided at a starting portion of the second page, modify the multipage message by moving the first portion included in the ending portion of the first page to the starting portion of the second page, and control the communication interface to transmit the modified multipage message including the first page and the second page, control the display to display a message including a plurality of multi-byte Unicode contents corresponding to user inputs, receive a request for transmission of the message, based on the request, identify that the message corresponds to a multipage message requiring transmission of a plurality of pages including a first page and a second page, if a first portion of one of the multi-byte Unicode contents is provided at an ending portion of the first page and a second portion of the one of the multi-byte Unicode contents is provided at a starting portion of the second page, modify the multipage message by moving the first portion included in the ending portion of the first page to the starting portion of the second page, and control the communication interface to transmit the modified multipage message including the first page and the second page, wherein the first portion and the second portion independently constitute undefined data as defined by Unicode and, when combined in the modified multipage message, the first portion and the second portion are recognizable as defined data as defined by Unicode.