How to troubleshoot CDO.Message error 8004020F

Symptom

When you send an email using CDOSYS you get the following error

error ‘8004020f’

The error code is returned by CDOSYS when the email is rejected by the mail server.

Make sure the ‘From’ email address is set correctly and is an email address etup on your account
Check that you have set the correct SMTP server.
Check that your hosting plan includes SMTP
If you use your ISPs SMTP server, check that they do not limit the use of their services.
Try using a SendUsing value of 1 (pickup) instead of 2 (port). E.g. the following line:
```
.Item(cdoSendUsingMethod) = cdoSendUsingPort
```
would become;
```
.Item(cdoSendUsingMethod) = cdoSendUsingPickup
```