Documentation request for Filter Incoming Emails by Domain

martin MHC

• June 19, 2020 09:12

Hello Using the "Filter Incoming Emails by Domain" system on WHM has proven to be fairly good at mitigating some but not all spam emails. However, could the documentation ( Filter Incoming Emails by Domain | cPanel & WHM Documentation ) add some clarity as to how much this can slow down the server's email handling process overall, Can I get an indicator as to the number of addresses set on this list that would start to then snail up the receiving of emails? I realise there is a lot of variables at work here but the primary cause is to have an indicator as to the number of domains to have on the list before finding the list causes a slowdown on email receiving. I believe that figure is around 2000 domains to check (from my memory of other similar process on Exim) but there's no reference as to if this relates (and if so how much) to this listing system. Cheers

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  martin MHC

  • June 19, 2020 21:43

  Not an answer to your question, but I wanted to make a quick mention here about the value of using custom RBLs in Exim Configuration Manager which you wouldn't need to manage manually. This may affect following responses.

  
  I think I've used these before the domain blocking ability came into WHM. I think I've got lazy and gradually moved over to using the Block by Domain system rather than the Exim system itself... I have a feeling this is what I was referencing that would -eventually - have a time delay on long lists.

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  keat63

  • June 22, 2020 07:53

  you're probably making a rod for your own back. Spammers register these cheap domains, send out millions of emails, then drop the domain to register another. It's a constant battle that you can't win doing it on your own. I'd also suggest going down the RBL route, let the engines do the bulk of the work for you, and you do it manually where the engines fail. Here is a list of the ones I use to decent effect.

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  cPanelLauren

  • June 23, 2020 17:01

  There's really no way I or anyone could provide you with an official response to how many domains need to be listed to block before it slows the system down. That'd be a trial and error sort of thing and could vary from user to user. Also, I want to point out that the suggestions to do RBL's to do the heavy lifting then manually block domains will remove a lot of the necessity to list some domains - which will in turn keep the list shorter.

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