Bitwarden e-mail verification problems with lets encrypt and local mail server

Hello everyone,

  1. I can ping my SMTP server from bitwarden-api container, also I can telnet the mailserver on port 25 and port 587. I tested the mail account via thunderbird and everything is working. If I use the mailserver in Bitwarden config I have the error message:

System.Net.Mail.SmtpException: Failure sending mail. —> System.Security.Authentication.AuthenticationException: The remote certificate is invalid according to the validation procedure.

But why? Letencrypt is valid certification and no other programs have problems with it.

  1. Second strange thing is, i have another test installation scenario. From the docker container e.g. bitwarden-api I can ping the docker host ip. On the docker host is installed an postfix server which allows to relay from the Bitwarden container network. So I can send mails without any problem and everything work. BUT after I restarted the docker container or use the command ./bitwarden rebuild and ./bitwarden start, the IPs and the hole network from the docker containers are changed. (bevor rebuild or restart the container e.g. have and after this the container have Each reboot change the IPs from the container one IP range up but why?

I can see that the ./bitwarden start delete docker default_network card. I have also two docker network cards.

docker0, this network card have always the same static ip no changes after reboot, start or rebuild

br-29a2b1f877c5, this network card changed every reboot, start or rebuild, the network card have than another name e.g. br-xxxxx and other IPs / network. Every rebuild, reboot or start +1 the IP range from this network card. (I tested it several times).

My problem is that I can not allow relay the docker containers via postfix on docker host because IP is always changing.