If you’ve received an error 553 message while sending email using an email program, either your Yahoo! Mail address or alternate email address (from a different Internet service) hasn’t been verified with Yahoo!.

To verify an email address with the Yahoo! SMTP Simple Mail Transfer Protocol, an Internet-standard protocol used by email programs to send mail to a remote computer service, please follow these instructions from within Yahoo! Mail:
 

1. In the upper-right of your Yahoo! Mail page, click Options.
2. From the Options menu, select Mail Options. The Mail Options page appears.
3. In the left pane, click Accounts, then in the right pane, click Add or edit an account. A separate Mail Accounts page appears.
4. Click Add. The Add Account wizard appears.
5. In the Account Name box, type a name for your own reference (for example, Work, School, Second Account), and click Continue.
6. Complete the following information:

• Name: The name you want the person receiving email from this address to see.
• Email: The alternate email address from which you would like to send email. We’ll send a confirmation code to this email address.

7. Click Continue. The Setup Mail Server page appears.
8. Click Skip This Step and continue to the next step in these instructions.

Note: You can add this information later by clicking Edit on the Mail Accounts page.

The Verify Account page appears.

9. Click Send Verification. A second Verify Account page appears, and email containing the confirmation code is sent to the account you named.
10. In the account you named, look for an email similar to the following:

Either click the link in the message or enter the confirmation code into the box in the second Verify Account page.

11. Click Verify Account. You are returned to the Mail Accounts page, where you can see your new account has been added.

Your alternate email address is now verified and can be used to send email through Yahoo! Mail or your email software.

Note: You can verify up to 10 alternate email addresses for every primary and secondary Yahoo! Mail ID.