On 4/16/20 3:58 PM, Jacky wrote:
> Hi,
> I am using Opensmtp 6.6.4p1. I am going to use Opensmtp as outgoing SMTP 
> server, and use POP before SMTP method for authentication.
> Is it possible for us to write and use custom filter ? If yes, is there any 
> information / resources available in the web ?
> Jacky

There are a couple of filters available, but I'm not aware of how
cross-platform available they are.
>From the OpenBSD ports tree there's the following written in go:
- https://github.com/poolpOrg/filter-rspamd
- https://github.com/poolpOrg/filter-senderscore
- spamassassin via https://www.umaxx.net
The latter has a couple of other filters, but aren't in the ports
tree, so probably have a little less testing.

I have written filter-dnsbl and filter-dkimsign in C:
- http://imperialat.at/dev/libopensmtpd/ (dependency for both)
- http://imperialat.at/dev/filter-dnsbl/
- http://imperialat.at/dev/filter-dkimsign/

I've got libopensmtpd to compile on Linux, but after that my need to get
them to work on Linux disappeared so the filters themselves never got 
there. If you want to use them I'm willing to help you set them up in 
your environment and commit the changes to my repo.

Other filters are relatively easy to write, but I don't think the
protocol is properly documented. You can look at this thread[0] as a
starting point, but there have been some minor changes since then, so
make sure to check your input.


[0] https://www.mail-archive.com/misc@opensmtpd.org/msg03727.html

Reply via email to