GetTor not responding to emails

GetTor isn't responding to emails. I just checked the logs and found the following errors:

2020-04-27T18:00:33+0000 [gettor#debug] Could not send email.
2020-04-27T18:00:33+0000 [gettor#info] Error sending email: [Failure instance: Traceback (failure with no frames): <class 'twisted.mail._except.SMTPDeliveryError'>: 501 No recipients accepted
        czjeff5655@!63.com: 501 5.1.3 Bad recipient address syntax
        >>> MAIL FROM:<gettor@torproject.org>
        <<< 250 2.1.0 Ok
        >>> RCPT TO:<redacted>
        <<< 501 5.1.3 Bad recipient address syntax
        
        ].
2020-04-27T18:00:33+0000 [twisted.mail.smtp.ESMTPSenderFactory#info] Stopping factory <twisted.mail.smtp.ESMTPSenderFactory object at 0x7fa3ac156940>

Looks like this started at 2020-04-17T16:08:57+0000. Perhaps there was a twisted update that broke it?