What does the this error message mean?
The from address does not match a verified Sender Identity. Mail cannot be sent until this error is resolved. Visit https://sendgrid.com/docs/for-developers/sending-email/sender-identity/ to see the Sender Identity requirements
These errors occur when attempting to send from an email address that is not a Verified Sender address. All mail sent through your account must contain a Verified Sender, or a sender using an Authenticated Domain, in the 'From' field.
What is a Verified Sender Identity?
A Sender Identity represents your “From” email address—the address your recipients will see as the sender of your emails. To ensure our customers maintain the best possible sender reputations and to uphold legitimate sending behavior, we require customers to verify their Sender Identities through their account they are sending from. Verified Sender Identity is required for all Twilio SendGrid accounts in order to send emails.
You can verify one or more Sender Identities using either Domain Authentication or Single Sender Verification.
Single Sender Verification:
Single Sender Verification is a fast way to verify your Sender Identity when you don’t have access to the DNS settings for your domain. Single Sender Verification does not provide the same authentication records as authenticating your domain that are necessary for good deliverability. Due to this, setting up Single Sender Verification is recommended for testing purposes, but not necessarily for production mail send.
We have more information on how to set up Single Sender Verification here: https://docs.sendgrid.com/ui/sending-email/sender-verification
Domain Authentication is our recommended form of verification. When a domain is authenticated in your SendGrid account it allows us to authenticate your emails with SPF and DKIM, two important security features that Inbox Service Providers look for when evaluating emails for delivery. Any sender address that uses an authenticated domain will automatically be considered a verified sender. If access to DNS records is a barrier for you, you can always start with Single Sender Verification and return to Domain Authentication once you obtain DNS access.
We have more information on how to set up Domain Authentication here: https://docs.sendgrid.com/ui/account-and-settings/how-to-set-up-domain-authentication
How to resolve the errors:
Once Verified Sender Identity is created for the 'From' address used for mail send in your account using one of the above methods the errors related to Sender Identity should be resolved.