I sent another email from the problem address and looked at the /var/log/qpsmtpd/current log.
View log files
/var/log/qpsmtpd/current: Viewed at Tue 14 Jul 2020 03:06:22 PM PDT.
Displaying lines matching: "k12.or.us".
2020-07-14 15:01:32.143606500 9785 Accepted connection 0/40 from 163.41.62.10 / fortimail.lesd.k12.or.us
2020-07-14 15:01:32.143672500 9785 Connection from fortimail.lesd.k12.or.us [163.41.62.10]
2020-07-14 15:01:36.810904500 9787 Accepted connection 2/40 from 163.41.62.10 / fortimail.lesd.k12.or.us
2020-07-14 15:01:36.810973500 9787 Connection from fortimail.lesd.k12.or.us [163.41.62.10]
I then filtered for 9785.
2020-07-14 15:01:32.143606500 9785 Accepted connection 0/40 from 163.41.62.10 / fortimail.lesd.k12.or.us
2020-07-14 15:01:32.143672500 9785 Connection from fortimail.lesd.k12.or.us [163.41.62.10]
2020-07-14 15:01:32.143967500 9785 in config(plugins)
2020-07-14 15:01:32.143985500 9785 config(plugins): hook returned (0,)
2020-07-14 15:01:32.145560500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.145561500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.146815500 9785 Loading hosts_allow from /usr/share/qpsmtpd/plugins/hosts_allow
2020-07-14 15:01:32.146922500 9785 hosts_allow hooking pre-connection
2020-07-14 15:01:32.147064500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.147065500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.147862500 9785 Loading peers from /usr/share/qpsmtpd/plugins/peers
2020-07-14 15:01:32.147873500 9785 in config(peers/0)
2020-07-14 15:01:32.147885500 9785 config(peers/0): hook returned (0,)
2020-07-14 15:01:32.148124500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.148124500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.173252500 9785 (init) peers: Loading tls ssl/cert.pem ssl/cert.pem ssl/cert.pem ssl/dhparam.pem from /usr/share/qpsmtpd/plugins/tls
2020-07-14 15:01:32.174593500 9785 (init) peers: Loading auth/auth_cvm_unix_local cvm_socket /var/lib/cvm/cvm-unix-local.socket enable_smtp no enable_ssmtp yes from /usr/share/qpsmtpd/plugins/auth/auth_cvm_unix_local
2020-07-14 15:01:32.175559500 9785 (init) peers: Loading earlytalker from /usr/share/qpsmtpd/plugins/earlytalker
2020-07-14 15:01:32.175917500 9785 (init) peers: Loading bogus_bounce from /usr/share/qpsmtpd/plugins/bogus_bounce
2020-07-14 15:01:32.176361500 9785 (init) peers: Loading count_unrecognized_commands 4 from /usr/share/qpsmtpd/plugins/count_unrecognized_commands
2020-07-14 15:01:32.177637500 9785 (init) peers: Loading relay from /usr/share/qpsmtpd/plugins/relay
2020-07-14 15:01:32.179122500 9785 (init) peers: Loading helo policy lenient reject naughty from /usr/share/qpsmtpd/plugins/helo
2020-07-14 15:01:32.181827500 9785 (init) peers: Loading resolvable_fromhost from /usr/share/qpsmtpd/plugins/resolvable_fromhost
2020-07-14 15:01:32.185853500 9785 (init) peers: Loading headers from /usr/share/qpsmtpd/plugins/headers
2020-07-14 15:01:32.186389500 9785 (init) peers: Loading loadcheck max_load 7 from /usr/share/qpsmtpd/plugins/loadcheck
2020-07-14 15:01:32.187105500 9785 (init) peers: Loading rhsbl from /usr/share/qpsmtpd/plugins/rhsbl
2020-07-14 15:01:32.188462500 9785 (init) peers: Loading sender_permitted_from reject 1 no_dmarc_policy 0 from /usr/share/qpsmtpd/plugins/sender_permitted_from
2020-07-14 15:01:32.190480500 9785 (init) peers: Loading dkim reject 0 from /usr/share/qpsmtpd/plugins/dkim
2020-07-14 15:01:32.192315500 9785 (init) peers: Loading dmarc reject 0 reporting 1 from /usr/share/qpsmtpd/plugins/dmarc
2020-07-14 15:01:32.193168500 9785 (init) peers: Loading dnsbl reject naughty from /usr/share/qpsmtpd/plugins/dnsbl
2020-07-14 15:01:32.193669500 9785 (init) peers: Loading naughty reject mail from /usr/share/qpsmtpd/plugins/naughty
2020-07-14 15:01:32.194172500 9785 (init) peers: Loading badmailfrom from /usr/share/qpsmtpd/plugins/badmailfrom
2020-07-14 15:01:32.194818500 9785 (init) peers: Loading badrcptto more_badrcptto badrcptto_ext from /usr/share/qpsmtpd/plugins/badrcptto
2020-07-14 15:01:32.195338500 9785 (init) peers: Loading check_goodrcptto extn - from /usr/share/qpsmtpd/plugins/check_goodrcptto
2020-07-14 15:01:32.195900500 9785 (init) peers: Loading rcpt_ok from /usr/share/qpsmtpd/plugins/rcpt_ok
2020-07-14 15:01:32.196427500 9785 (init) peers: Loading virus/pattern_filter check=patterns action=deny from /usr/share/qpsmtpd/plugins/virus/pattern_filter
2020-07-14 15:01:32.237485500 9785 (init) peers: Loading tnef2mime from /usr/share/qpsmtpd/plugins/tnef2mime
2020-07-14 15:01:32.239770500 9785 (init) peers: Loading spamassassin reject_threshold 12 from /usr/share/qpsmtpd/plugins/spamassassin
2020-07-14 15:01:32.241450500 9785 (init) peers: Loading virus/clamdscan scan_all yes clamd_socket /var/clamav/clamd.socket defer_on_error yes max_size 25000 from /usr/share/qpsmtpd/plugins/virus/clamdscan
2020-07-14 15:01:32.242173500 9785 (init) peers: Loading queue/qmail-queue from /usr/share/qpsmtpd/plugins/queue/qmail-queue
2020-07-14 15:01:32.242251500 9785 peers hooking valid_auth
2020-07-14 15:01:32.242261500 9785 peers hooking set_hooks
2020-07-14 15:01:32.242371500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.242372500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.242541500 9785 in config(tls_ciphers)
2020-07-14 15:01:32.242541500 9785 config(tls_ciphers): hook returned (0,)
2020-07-14 15:01:32.242661500 9785 in config(tls_protocols)
2020-07-14 15:01:32.242661500 9785 config(tls_protocols): hook returned (0,)
2020-07-14 15:01:32.242785500 9785 tls: ciphers: HIGH:!SSLv2:!ADH:!aNULL:!MD5:!RC4
2020-07-14 15:01:32.243915500 9785 tls hooking connect
2020-07-14 15:01:32.243926500 9785 tls hooking ehlo
2020-07-14 15:01:32.243972500 9785 tls hooking helo
2020-07-14 15:01:32.243985500 9785 tls hooking rcpt
2020-07-14 15:01:32.244032500 9785 tls hooking mail
2020-07-14 15:01:32.244032500 9785 tls hooking data
2020-07-14 15:01:32.244100500 9785 tls hooking post-connection
2020-07-14 15:01:32.244110500 9785 tls hooking unrecognized_command
2020-07-14 15:01:32.244190500 9785 (set_hooks) running plugin: peers
2020-07-14 15:01:32.244289500 9785 in config(peers/0)
2020-07-14 15:01:32.244290500 9785 config(peers/0): hook returned (0,)
2020-07-14 15:01:32.244527500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.244527500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.244637500 9785 in config(peers/0)
2020-07-14 15:01:32.244637500 9785 config(peers/0): hook returned (0,)
2020-07-14 15:01:32.244847500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.244847500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.245102500 9785 peers hooking valid_auth
2020-07-14 15:01:32.245109500 9785 peers hooking set_hooks
2020-07-14 15:01:32.245161500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.245162500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.245342500 9785 logging::logterse hooking queue
2020-07-14 15:01:32.245386500 9785 logging::logterse hooking deny
2020-07-14 15:01:32.245406500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.245419500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.245525500 9785 in config(tls_ciphers)
2020-07-14 15:01:32.245538500 9785 config(tls_ciphers): hook returned (0,)
2020-07-14 15:01:32.245610500 9785 in config(tls_protocols)
2020-07-14 15:01:32.245623500 9785 config(tls_protocols): hook returned (0,)
2020-07-14 15:01:32.245698500 9785 tls: ciphers: HIGH:!SSLv2:!ADH:!aNULL:!MD5:!RC4
2020-07-14 15:01:32.246351500 9785 tls hooking connect
2020-07-14 15:01:32.246376500 9785 tls hooking ehlo
2020-07-14 15:01:32.246395500 9785 tls hooking helo
2020-07-14 15:01:32.246428500 9785 tls hooking rcpt
2020-07-14 15:01:32.246448500 9785 tls hooking mail
2020-07-14 15:01:32.246467500 9785 tls hooking data
2020-07-14 15:01:32.246496500 9785 tls hooking post-connection
2020-07-14 15:01:32.246516500 9785 tls hooking unrecognized_command
2020-07-14 15:01:32.246542500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.246556500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.246781500 9785 auth::auth_cvm_unix_local: skip: enable_smtp=no
2020-07-14 15:01:32.246799500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.246812500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.247016500 9785 earlytalker hooking connect
2020-07-14 15:01:32.247037500 9785 earlytalker hooking data
2020-07-14 15:01:32.247060500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.247073500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.247235500 9785 bogus_bounce hooking data_post
2020-07-14 15:01:32.247300500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.247314500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.247500500 9785 count_unrecognized_commands hooking unrecognized_command
2020-07-14 15:01:32.247541500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.247555500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.247667500 9785 relay hooking connect
2020-07-14 15:01:32.247767500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.247780500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.248030500 9785 helo hooking helo
2020-07-14 15:01:32.248050500 9785 helo hooking ehlo
2020-07-14 15:01:32.248068500 9785 helo hooking data_post
2020-07-14 15:01:32.248090500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.248104500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.248257500 9785 resolvable_fromhost hooking mail
2020-07-14 15:01:32.248363500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.248376500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.248546500 9785 headers hooking data_post
2020-07-14 15:01:32.248613500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.248627500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.248899500 9785 loadcheck hooking connect
2020-07-14 15:01:32.248923500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.248936500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.249079500 9785 rhsbl hooking mail
2020-07-14 15:01:32.249155500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.249169500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.273947500 9785 sender_permitted_from hooking mail
2020-07-14 15:01:32.273960500 9785 sender_permitted_from hooking data_post_headers
2020-07-14 15:01:32.273972500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.274015500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.291232500 9785 dkim hooking data_post_headers
2020-07-14 15:01:32.291243500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.291252500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.374191500 9785 dmarc hooking data_post_headers
2020-07-14 15:01:32.374211500 9785 dmarc hooking data_post
2020-07-14 15:01:32.374259500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.374259500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.374434500 9785 dnsbl hooking connect
2020-07-14 15:01:32.374498500 9785 dnsbl hooking rcpt
2020-07-14 15:01:32.374584500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.374584500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.374813500 9785 naughty hooking data_post
2020-07-14 15:01:32.374823500 9785 naughty: registering hook mail
2020-07-14 15:01:32.374829500 9785 naughty hooking mail
2020-07-14 15:01:32.374875500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.374876500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.375045500 9785 badmailfrom hooking mail
2020-07-14 15:01:32.375116500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.375117500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.375277500 9785 badrcptto hooking rcpt
2020-07-14 15:01:32.375348500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.375348500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.375562500 9785 check_goodrcptto hooking rcpt
2020-07-14 15:01:32.375569500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.375602500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.375741500 9785 rcpt_ok hooking rcpt
2020-07-14 15:01:32.375817500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.375817500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.376016500 9785 virus::pattern_filter hooking data_post
2020-07-14 15:01:32.376040500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.376053500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.376244500 9785 tnef2mime hooking data_post
2020-07-14 15:01:32.376270500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.376283500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.376496500 9785 spamassassin hooking data_post
2020-07-14 15:01:32.376522500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.376535500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.379000500 9785 virus::clamdscan hooking data_post
2020-07-14 15:01:32.379027500 9785 in config(plugin_dirs)
2020-07-14 15:01:32.379042500 9785 config(plugin_dirs): hook returned (0,)
2020-07-14 15:01:32.379229500 9785 queue::qmail_2dqueue hooking queue
2020-07-14 15:01:32.379461500 9785 Plugin peers, hook set_hooks returned DECLINED,
2020-07-14 15:01:32.379520500 9785 (connect) running plugin: tls
2020-07-14 15:01:32.379551500 9785 (connect) tls: skip, not SMTPS
2020-07-14 15:01:32.379578500 9785 Plugin tls, hook connect returned DECLINED,
2020-07-14 15:01:32.379591500 9785 (connect) running plugin: earlytalker
2020-07-14 15:01:33.380782500 9785 (connect) earlytalker: pass, not spontaneous
2020-07-14 15:01:33.380795500 9785 Plugin earlytalker, hook connect returned DECLINED,
2020-07-14 15:01:33.380814500 9785 (connect) running plugin: relay
2020-07-14 15:01:33.380864500 9785 in config(norelayclients)
2020-07-14 15:01:33.380865500 9785 config(norelayclients): hook returned (0,)
2020-07-14 15:01:33.381038500 9785 (connect) relay: no match in norelayclients
2020-07-14 15:01:33.381038500 9785 in config(relayclients)
2020-07-14 15:01:33.381048500 9785 config(relayclients): hook returned (0,)
2020-07-14 15:01:33.381225500 9785 (connect) relay: no cidr match
2020-07-14 15:01:33.381225500 9785 in config(morerelayclients)
2020-07-14 15:01:33.381235500 9785 config(morerelayclients): hook returned (0,)
2020-07-14 15:01:33.381307500 9785 (connect) relay: no octet match
2020-07-14 15:01:33.381308500 9785 (connect) relay: skip, no match
2020-07-14 15:01:33.381328500 9785 Plugin relay, hook connect returned DECLINED,
2020-07-14 15:01:33.381339500 9785 (connect) running plugin: loadcheck
2020-07-14 15:01:33.381433500 9785 (connect) loadcheck: /proc/loadavg reported: 0.27
2020-07-14 15:01:33.381455500 9785 Plugin loadcheck, hook connect returned DECLINED, continuing with load: 0.27
2020-07-14 15:01:33.381462500 9785 (connect) running plugin: dnsbl
2020-07-14 15:01:33.381529500 9785 (connect) dnsbl: RBLSMTPD not set for 163.41.62.10
2020-07-14 15:01:33.381530500 9785 in config(dnsbl_allow)
2020-07-14 15:01:33.381540500 9785 config(dnsbl_allow): hook returned (0,)
2020-07-14 15:01:33.381660500 9785 in config(dnsbl_zones)
2020-07-14 15:01:33.381661500 9785 config(dnsbl_zones): hook returned (0,)
2020-07-14 15:01:33.381837500 9785 (connect) dnsbl: Checking 10.62.41.163.zen.spamhaus.org for TXT record
2020-07-14 15:01:33.687919500 9785 (connect) dnsbl: Checking 10.62.41.163.dnsbl.njabl.org for TXT record
2020-07-14 15:02:04.000102500 9785 (connect) dnsbl: dnsbl.njabl.org query failed: query timed out
2020-07-14 15:02:04.000114500 9785 (connect) dnsbl: Checking 10.62.41.163.whois.rfc-ignorant.org for TXT record
2020-07-14 15:02:04.095979500 9785 (connect) dnsbl: pass
2020-07-14 15:02:04.096000500 9785 Plugin dnsbl, hook connect returned DECLINED,
2020-07-14 15:02:04.096059500 9785 in config(smtpgreeting)
2020-07-14 15:02:04.096059500 9785 config(smtpgreeting): hook returned (0,)
2020-07-14 15:02:04.096196500 9785 220 larry-server.mrlistersir.com ESMTP
2020-07-14 15:02:04.096227500 9785 in config(timeoutsmtpd)
2020-07-14 15:02:04.096242500 9785 config(timeoutsmtpd): hook returned (0,)
2020-07-14 15:02:04.096409500 9785 DESTROY called by Qpsmtpd::TcpServer, /usr/share/perl5/vendor_perl/Qpsmtpd/TcpServer.pm, 135
2020-07-14 15:02:04.096456500 9785 (post-connection) running plugin: tls
2020-07-14 15:02:04.096507500 9785 Plugin tls, hook post-connection returned DECLINED,
2020-07-14 15:02:04.097361500 9785 DESTROY called by main, /usr/bin/qpsmtpd-forkserver, 0
2020-07-14 15:02:04.834608500 2360 cleaning up after 9785
Seems like there are several lines with the word "decline". Is that part of the issue?