Error: "550 5.7.1 Sender ID (PRA) Not Permitted" after emailing a TechMail recipient


After sending email to a recipient with a TechMail address (, you may receive an error message similar to the following:

550 5.7.1 Sender ID (PRA) Not Permitted


When the TechMail system receives email from the Internet, it uses a feature called Sender ID to validate the identity of senders from outside mail systems. Any of the following could result from the Sender ID validation process and cause the error above:

Possible cause #1

The domain (the portion after the @ sign) from the alleged sender's address may not resolve via DNS if it is an invalid email domain.

Possible cause #2

The sending domain's SPF record may instruct the TechMail system to reject any messages sent from unauthorized hosts. The TechMail system will honor the requests in such cases.

Possible cause #3

The "From" address ends in, but the email did not originate from an authorized TechMail sending server. The TTU SPF record instructs receiving mail systems to reject any messages sent from unauthorized hosts. (See the previous bullet point.)


Follow the solution detailed below for your particular cause.

Resolution for Cause #1

If the domain from the alleged sender's address could not be resolved via DNS (Cause #1 above) but it is a valid address, the administrators of the sending mail system's DNS records may need to correct some settings. This will allow the domain records for the sending email system to be resolved properly via DNS.

Resolution for Cause #2

If the sending domain's SPF record instructed the TechMail system to reject unauthorized hosts (Cause #2 above), TechMail will simply honor their instruction. There is nothing that TechMail administrators will do or can do in this case. The message either came from an unauthorized mailer and was rejected as expected or the sending mailer's SPF record is incorrect and needs to be updated by system administrators of the sending domain.

TIP: Learn more about SPF or look up a domain's SPF record.

Resolution for Cause #3

If the sender is attempting to send from a TechMail address (Cause #3 above), they must correct their settings to send the email through authorized TechMail servers.

Websites where you can "email yourself a link" or "send this to a friend" almost always spoof the sending address. For cases such as this, the TTU IT Division recommends using a non-TTU email address such as (consumer version), Yahoo, or Gmail.


Once the settings are corrected by the sender or the administrators of the sending domain, TechMail should be able to receive email from the sender.