You're sending this from a different address or alias using the 'Send mail as' feature
In some cases, when you try to send an email message you may see this message – “You’re sending this from a different address or alias using the ‘Send mail as‘ feature. The settings for your ‘Send mail as‘ account are misconfigured or out of date. Check those settings and try resending.”
This warning would occur if there is a difference between the e-mail address configured to send messages in your SMTP settings, and the e-mail address configured into your E-mail From field. Due to spam precaution measures, we do not allow sending e-mail messages from a domain name that is not part of the domain you have configured in your SMTP settings.
To resolve the problem, make sure that the e-mail From field settings are configured to work with an e-mail address using the same domain name as the one used in your website’s or local e-mail client SMTP settings.