I currently have a webmin server installed with squid proxy and I don’t receive emails through outlook or thunderbird.
I opened the port IMAP Port: 993 POP3 Port: 995, SMTP Port: 465 and it still blocks the entry and exit of emails from the mail client.
I receive mail in my mail client with the same configuration without the webmin server but behind the webmin the client does not connect to the mail server