Why am I getting these notification errors by email and sms"sendemail:137 and sendemail:460"?

[GiovanniJardine]

My notification isn´t work, i have this two errors in the index=_internal

-0600 ERROR sendemail:137 - Sending email. subject="prueba SEP114A", " server="smtp.gmail.com:587"

ERROR sendemail:460 - [Errno -2] Name or service not known while sending mail to.