I have the successfully built the latest source code of Tcl TLS (https://core.tcl-lang.org/tcltls/info/4dfbd811b4a163f7) with OpenSSL 3.0.18 on both Linux and Windows. While the simple testing failed, the test worked fine with old 1.7/1.8 with OpenSSL 1.1.1k.
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C:\xtor\sbin>tcl \devmap\tcltls\Email.tcl
::mime::1
Trying smtp.sina.com...
<-- 220 smtp-250-22.smtpsmail.fmail.yf.sinanode.com ESMTP
--> EHLO cnshntwu02 (wait upto 300 seconds)
<-- 250-smtp-250-22.smtpsmail.fmail.yf.sinanode.com
<-- 250-AUTH LOGIN PLAIN
<-- 250-AUTH=LOGIN PLAIN
<-- 250-STARTTLS
<-- 250 8BITMIME
--> STARTTLS (wait upto 300 seconds)
<-- 220 ready for tls
--> EHLO cnshntwu02 (wait upto 300 seconds)
^C


The script goes like,

#Initialize Email Option Array
set aMail(SERVER) "smtp SERVER address"
set aMail(PORT) 587
set aMail(FROM) "xxx@xxxm" 
set aMail(FROM_NAME) "System (c) - Do Not Reply"
set aMail(TO) "wrenashe@gmail.com"
set aMail(SUBJ) "Tcltls-2.0b2 test result"
set aMail(MSG) "Tcltls-2.0b2 test result"
set aMail(IMPORTANCE) ""
set sEmailRc "" 
set oMailToken [mime::initialize -canonical text/html -string $aMail(MSG)]
puts $oMailToken
set sMailUser "cistesting@sina.com"
set sMailPass "Password01&"
if {[catch { set sEmailRc [smtp::sendmessage $oMailToken \
    -originator $aMail(FROM) \
    -recipients $aMail(TO) \
    -servers $aMail(SERVER) \
    -ports $aMail(PORT) \
	-username $sMailUser \
	-password $sMailPass \
    -header [list From "\"$aMail(FROM_NAME)\" <$aMail(FROM)>"] \
    -header [list To $aMail(TO)] \
    -header [list Importance $aMail(IMPORTANCE)] \
    -header [list Subject $aMail(SUBJ)] -usetls 1  -debug 1 ]} sErrMsg]} {
	puts "Notification failed - $sErrMsg"
} else {
    if { $sEmailRc !=  "" } {
      puts "Notification failed - $sEmailRc"
    } else {
      puts "Notification sent - $aMail(TO)"
    }
}
mime::finalize $oMailToken
unset oMailToken