An electronic device, comprising: a communication interface; an input interface including a microphone, an output interface including a speaker at least one processor; and at least one memory, wherein instructions stored in the memory, are executable by the at least one processor to: receive a first message through the communication interface from an external device; in response to receiving a first user input associated with the first message through the input interface, convert first text included in the first message into speech; output the speech using the output interface; determine whether to execute an additional operation associated with the first message, based on at least one of a state of the electronic device, the first message, and a second user input received via the microphone; and initiate a conversational mode (1350, 2060) for executing the additional operation based at least partly on the determination, wherein the conversational mode is initiated when detecting that an attribute that the first message includes a reply request is included in the first message, wherein, in the conversational mode, when the end point of an user input through the microphone is detected, transmit a message corresponding to the user input to the external device, and, in the conversational mode, when a message is received from the external device, perform a text-to-speech function to output the content of the received message without additional user input. a communication interface; an input interface including a microphone, an output interface including a speaker at least one processor; and at least one memory, wherein instructions stored in the memory, are executable by the at least one processor to: receive a first message through the communication interface from an external device; in response to receiving a first user input associated with the first message through the input interface, convert first text included in the first message into speech; output the speech using the output interface; determine whether to execute an additional operation associated with the first message, based on at least one of a state of the electronic device, the first message, and a second user input received via the microphone; and initiate a conversational mode (1350, 2060) for executing the additional operation based at least partly on the determination, wherein the conversational mode is initiated when detecting that an attribute that the first message includes a reply request is included in the first message, wherein, in the conversational mode, when the end point of an user input through the microphone is detected, transmit a message corresponding to the user input to the external device, and, in the conversational mode, when a message is received from the external device, perform a text-to-speech function to output the content of the received message without additional user input. receive a first message through the communication interface from an external device; in response to receiving a first user input associated with the first message through the input interface, convert first text included in the first message into speech; output the speech using the output interface; determine whether to execute an additional operation associated with the first message, based on at least one of a state of the electronic device, the first message, and a second user input received via the microphone; and initiate a conversational mode (1350, 2060) for executing the additional operation based at least partly on the determination, wherein the conversational mode is initiated when detecting that an attribute that the first message includes a reply request is included in the first message, wherein, in the conversational mode, when the end point of an user input through the microphone is detected, transmit a message corresponding to the user input to the external device, and, in the conversational mode, when a message is received from the external device, perform a text-to-speech function to output the content of the received message without additional user input.