Oké some editing in the hope to be enough specific: We set up server 1, partly with the help of goPanel2 (desktop adminpanel for Mac) and Terminal.
Server1 - Now Backend with server 2 added
One Ubuntu 20 server as back-end with Nginx (and Apache available), MariaDB, PHP, ftp and Postfix/Dovecot bundle, Fail2Ban, the domains (/gopanel/sites/domain_com) & emails (all installed through goPanel)
Server2 - Front
One Debian 10 Nginx reverse proxy server, domains (connected via vhost files in Nginx's sites-available - /var/www/html), the SSL installed (from Letsencrypt with the Nginx plugin) and Fail2Ban - so nothing else
In the hosting provider there is a txt record is v=spf1 a mx ip4:fromserver1 -all and one for _dmarc: v=DMARC1; p=none; rua=mailto:admin@domain.com; ruf=mailto:admin@domain.com; fo=1 p=quarantine MX record is from the own domain: domain.com.
When only server 1 was working I could receive the emails in my Apple mail, there were no problems. Now that we installed server 2, I get the error: "Unable to verify account name or password."
We are sure it has to do with the Dovecot auth but seem not to be able to find what exactly goes wrong.
Syslog error:
Oct 6 postfix/smtpd[104307]: warning: unknown[ip]: SASL LOGIN authentication failed: UGFzc3dvcmQ6
Oct 6 postfix/smtpd[104307]: disconnect from unknown[ip] ehlo=1 auth=0/1 quit=1 commands=2/3
Anyone who has set up a reverse proxy this way and have some insights for us?
