This tool is used to check SMTP connection with an email server or smtp server
The SMTP Test can help you identify where your send mail request is encountering issues.
Depending on the mail server, you’ll receive a series of responses, possibly with comments to help explain them.
There are also a number of SMTP codes:
Code: 220 - Message: Service ready
Code: 221 - Message: Service closing transmission channel
Code: 250 - Message: Requested mail action okay, completed
Code: 251 - Message: User not local - forward to [path]