SMTP services fail with app password on Yahoo servers

We have noticed an increase in calls with customers scanning email utilizing the SMTP servers of Yahoo. The message is simple “Job failed. No messages were sent. Could not communicate with the sending mail server (SMTP). Contact your System Administrator.” At first, it seemed the messages never made it over to the Yahoo servers, but today I dug in a little further and noticed the test e-mails from the machines and the actual e-mails from the user interfaces were actually being transmitted to the servers – however, they were stuck in the Drafts folder. I examined the message and noticed each time there was a NULL e-mail address in the CC field.

Since I saw this NULL character in the CC field, I decided to test this by sending an e-mail from the machine’s user interface with a TO and a CC address, and to my astonishment, it was completed successfully. I have reached out to Xerox which said they were aware of an ongoing issue with Yahoo SMTP servers since Rogers was moving to their servers, but haven’t seen this exact issue. I have also contacted Yahoo support, or should I say I tried, but without a paid subscription to their plus service I was only able to get extremely basic information or refer to or the online chat – which was completely useless.

As of this writing, a workaround is to use the Auto Add Me to the CC field or to add an e-mail address to the TO and CC field when sending an e-mail. If I get any updates or find anything else additional, I will be sure to update this post.

SMTP Server:
Port: 587 w/ STARTTLS
Username: full yahoo email address
Password: app password

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