US Patent 7313385 E-mail distribution control method and mail server

When gateway server 30 receives an email, which is addressed to mobile station 10, gateway server 30 transmits an email arrival notice to mobile station 10. When gateway server 30 receives an acknowledgement response (referred to as ‘Ack’ hereinafter) responding to the email arrival notice from mobile packet communication network 20, gateway server 30 evaluates the status of mobile station 10 on the basis of the type of Ack, and determines whether to transmit the email or not. Moreover, gateway server 30 modifies the time interval for retransmitting the email arrival notice to mobile station 10 according to the status of mobile station 10 when the transmission of the email arrival notice fails.