ssl-handshake takes forever running opensmtpd on top of docker

[alexanderharm]

i intended to use opensmtpd as a mail relay inside an organisation but even after serveral hours i somehow fail to get the whole thing working. the goal is to simply relay all authorised submissions to the provider and set a generic from address. my config:

pki my.hostname.tld cert "/etc/mail/OpenSMTP-Relay.crt"
pki my.hostname.tld key "/etc/mail/OpenSMTP-Relay.key"

table usercreds "/etc/mail/usercreds"
table relaycreds "/etc/mail/relaycreds"

listen on 0.0.0.0 smtps protocols "legacy" ciphers "compat" pki my.hostname.tld hostname my.hostname.tld auth <usercreds>
listen on 0.0.0.0 port 587 tls-require protocols "legacy" ciphers "compat" pki my.hostname.tld hostname my.hostname.tld auth <usercreds>

action "relay" relay host "smtps:https://[email protected]" auth <relaycreds> mail-from "[email protected]"
match auth from any for any action "relay"

config check reports ok and the service is up and running. however, establishing a ssl-handshake seems to take forever:

openssl s_client -connect 192.168.42.2:465
Connecting to 192.168.42.2
CONNECTED(00000004)
<wait for 10 to 15 minutes>
Can't use SSL_get_servername
depth=0 C=DE,...

there is not much in the logs:

20d98cd51ee58608 smtp disconnected reason="io-error: handshake failed: No error information"

i'm testing with the official docker image (master at this point but also tried the others).

am i missing something in my conf?