[Xymon] smtps checks seem to always fail

[Lists]

I have a mail server at host.effortlessis.com set up with LetsEncrypt 
certificates. Whenever I turn on the smtps test, I get a status RED from xymon 
with the error message: 

Service smtps on host.effortlessis.com is not OK : Service listening but 
unavailable (SSL error)

Any idea how to resolve this?  

Some config details that might help: 

xymon-4.3.30 on CentOS Linux release 7.9.2009 (Core)
No issues with smtp test. 

hosts.cfg 
51.68.205.149 host.effortlessis.com # smtp smtps conn imaps sni https://
host.effortlessis.com 

server/etc/protocols.cfg
[smtps]
   send "ehlo xymonnet\r\nquit\r\n"
   expect "220"
   options ssl,banner
   port 465

The SSL certificate passes fine if I check it manually. (monitor is the name of 
the xymon host and I am running this test as the xymon daemon user) 

[xymon at monitor ~]$ echo "quit" | openssl s_client -starttls smtp -connect 
host.effortlessis.com:465 > /dev/null
depth=3 O = Digital Signature Trust Co., CN = DST Root CA X3
verify return:1
depth=2 C = US, O = Internet Security Research Group, CN = ISRG Root X1
verify return:1
depth=1 C = US, O = Let's Encrypt, CN = R3
verify return:1
depth=0 CN = host.effortlessis.com
verify return:1
250 SMTPUTF8
DONE
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