Kolab 16 on Ubuntu rejecting emails from Amazon

[Eric B Munson]

All I am seeing postfix reject emails coming from Amazon.  The postfix 
logs show the following when such an email come in:

Oct 21 09:57:41 machine postfix/smtpd[24703]: connect from 
a13-34.smtp-out.amazonses.com[54.240.13.34]
Oct 21 09:57:42 machine postfix/smtpd[24703]: 48F995CADD9: 
client=a13-34.smtp-out.amazonses.com[54.240.13.34]
Oct 21 09:57:42 machine postfix/smtpd[24703]: 48F995CADD9: reject: DATA 
from a13-34.smtp-out.amazonses.com[54.240.13.34]: 554 5.7.1 <DATA>: Data 
command rejected: Recipient access denied; 
from=<20171021135739619e64957d31417aa1e1f80192a0p0na at bounces.amazon.com> 
to=<user at domain.tld> proto=ESMTP helo=<a13-34.smtp-out.amazonses.com>

I don't know exactly what is going on, but this problem looks the same: 
https://kolab.org/hub/topic/260/google-mails-rejected/1 and the sender 
address is 66 characters.  The forum post has a proposed solution but it 
is missing the details (and this feels like it should have a bug 
opened).  How can I work around this now?

Thanks,
Eric