One Error in smtp?

Hello. I have a php program created with yii2. When I try to access it, it is giving me this error: CHTTpException:
1- SMTP Error: the following recipients failed:
2- The mail server is temporarily disabled. try again later.

It could be that the program stops working due to SMTP failures (although it was verified and continues to work). ?
In the server i have php 5 in Debian 8.