sendgrid error after changing settings

When a moodle server had its domain changed, the sendgrid account it used to send password reset emails was still using the old domain. When the "From" email id was changed, sendgrid gave an error,

550 The from address does not match a verified Sender Identity. 

Two different ways to verify:

Domain Authentication, which is their preferred way - by adding three CNAME records and one txt record - and

Single Sender Verification