> On 23 Jan 2025, at 17:55, Wietse Venema via Postfix-users
> <postfix-users@postfix.org> wrote:
>
> Gerben Wierda via Postfix-users:
>> I was wondering, suppose I have a user like this:
>>
>> f...@bar.com is the account name
>> foo.lastn...@bar.com is the incoming alias and the outgoing canonical
>>
>> Could I force incoming mail to accept the alias form, but not
>> accept the account form? I.e. f...@bar.com as address is blocked,
>> but foo.lastn...@bar.com is accepted and delivered to f...@bar.com
>>
>> The spammers that send to my systems use the account form (and not
>> the alias/canonical) a lot, that's why I'm asking
>>
>> I can of course create a new account form (a...@bar.com) and use
>> aliases/canonicals on that, but that might not take hold in the
>> long term and I would have to let users change their auth settings
>> (which now is user 'foo' and 'password')
>
> Could this be as simple as an smtpd_recipient_restriction
>
> /etc/postfix/main.cf
> smtpd_recipient_restriction =
> ...
> reject_unauth_destination
> check_recipient_access pcre:/etc/postfix/reject-account.pcre
> ...
>
> /etc/postfix/reject-account.pcre:
> /^[^.]+@example\.com$/ reject must use the first.last form
>
> Or the hard-core form:
>
> /etc/postfix/main.cf
> smtpd_recipient_restriction =
> ...
> reject_unauth_destination
> check_recipient_access pcre:{{/^[^.]+@example\.com$$/
> reject must use the first.last form}}
> ...
>
> If this is intended only for *some* accounts, then you need one
> to enumerate the forbidden forms.
If I understand the documentation correctly, this will reject (I'm planning for
'discard' to get rid of the backscatter) the entire message for all recipients,
including valid ones. If I want to discard it only for one of the recipients, I
need to use the transport table. So, might it be enough to have a (non-pcre)
entry:
usern...@example.com discard:
in the transport table? Discard is not mentioned in the man page for
transport(5), but it is mentioned in th eman page for access(5)
Gerben
>
> Wietse
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