rejected delivery
Emails to me are being rejected by the yahoo servers. See undelivered messages pasted:
This is the mail system at host gateway13.unifiedlayer.com.
I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.
For further assistance, please send mail to postmaster.
If you do so, please include this problem report. You can
delete your own text from the attached returned message.
The mail system
kjchoi462@yahoo.com: delivery temporarily suspended: lost connection with
mta7.am0.yahoodns.net[67.195.204.77] while sending RCPT TO
Reporting-MTA: dns; gateway13.unifiedlayer.com
X-Postfix-Queue-ID: 648D2201182AD
X-Postfix-Sender: rfc822; john@jksig.com
Arrival-Date: Fri, 30 Aug 2019 20:26:10 -0500 (CDT)
Final-Recipient: rfc822; kjchoi462@yahoo.com
Original-Recipient: rfc822;kjchoi462@yahoo.com
Action: failed
Status: 4.4.2
Diagnostic-Code: X-Postfix; delivery temporarily suspended: lost connection
with mta7.am0.yahoodns.net[67.195.204.77] while sending RCPT TO

Sorry for the inconvenience this may have caused you. From the looks of it, it seems like something our Postmaster Team can help you out with. You can reach them: http://postmaster.yahoo.com