Hi list, I'm having an issue with my Postfix configuration: Currently I've it set up so that one authentication SASL login (e.g., [email protected]) supports multiple virtual email addresses (e.g., [email protected] but also [email protected], [email protected]).
Once authenticated with [email protected], the envelope sender ("MAIL FROM") is restricted to only the permissible variants. However, as I've now painfully found out, when in Thunderbird someone uses the "Custom From Address" feature, it doesn't change the envelope sender, but only the actual "From" header field. This means, I have the following situation: Auth: [email protected] Envelope from: [email protected] Header 'From': [email protected] One of my customers used a gmail address in the header "From", sent an email to @hotmail.com and now my mailserver is permablocked at Microsoft for bad reputation. How can I ensure in the future that the same checks are applied to the Header "From" field that are also applied to the evelope "From" field? Thanks, Johannes
