SMTP Error 501
Description: Syntax error in parameters or arguments.
What does this mean?
This is similar to SMTP Error #500, although this is specific to the additional ‘parameters’ or options that are being used.
How to fix SMTP Error 501?
This is most commonly an issued with an incorrect/invalid email address, however can also be due to anti-spam filters as referenced in the similar SMTP Error # 500. If you’ve confirmed a correct email address, I suggest reviewing the fixes for SMTP Error # 500.
SMTP Error 501 Examples
Remote host said: 501 Invalid Address