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Hello,
we have some problems with spam, that is directly send to the server IP, bypassing the external mailfilter specified in the MX. Whats the best way to prevent this?
There are some methods to prevent spam directly send to the server, like changing port 25 to an alternative port and then close port 25, or set the firewall to restrict access to the mailserver to the IPs of the external mailfilter. The problem with this is, as far as I see, that we would lock out the users, that have mailboxes/accounts on our servers and send emails by connecting to SMTP, often from dynamic IPs.
Is there a way to solve this problem by configuring Postfix, for example using "smtpd_client_restrictions" to restrict access to the external mailfilter, or would this cause the same problem with users on the server, trying to send emails by their accounts? Is it possible for Postfix to distinguish this, so we could restrict access to accept mails only from the external mailfilter, but still allow users with mail-accounts on our servers to connect and send emails?
Thank you,
Flux24
we have some problems with spam, that is directly send to the server IP, bypassing the external mailfilter specified in the MX. Whats the best way to prevent this?
There are some methods to prevent spam directly send to the server, like changing port 25 to an alternative port and then close port 25, or set the firewall to restrict access to the mailserver to the IPs of the external mailfilter. The problem with this is, as far as I see, that we would lock out the users, that have mailboxes/accounts on our servers and send emails by connecting to SMTP, often from dynamic IPs.
Is there a way to solve this problem by configuring Postfix, for example using "smtpd_client_restrictions" to restrict access to the external mailfilter, or would this cause the same problem with users on the server, trying to send emails by their accounts? Is it possible for Postfix to distinguish this, so we could restrict access to accept mails only from the external mailfilter, but still allow users with mail-accounts on our servers to connect and send emails?
Thank you,
Flux24