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From Daniele Duca <>
Subject Re: Check for valid MX of sender and rspamd testing
Date Tue, 10 Apr 2018 07:41:18 GMT
On 09/04/2018 20:40, Sebastian Arcus wrote:

> This might not really answer your question, but I've had really good 
> results leaving all this to the MTA (Exim in my case). I actually go 
> for the whole hog full callout verification - checking with the MX 
> that the sender really exists. I know that some people are against 
> this and say that you get blacklisted - but I've been doing this for 
> about 8 months on 4 sites and it has worked very well. I have a local 
> full callout verification whitelist - to skip callout verification 
> mainly for Microsoft operated domains - which will blacklist you at 
> the drop of the hat.
Hello Sebastian,

I'm curious about this approach. I never tried it, but, assuming that 
you check the MX of the envelope from domain, how do you deal with 
poorly-configured-but-legit VPS that use, in example, 
www-data@hostname.of.the.server ? I have live examples of wordpress and 
vbulletin installations that have not existent envelope from mailboxes 
or VPS hostnames without MX records. There are also other services that 
actively send email in the form of "". If I understood 
correctly, your approach would heavily penalize these senders.

I know that in the ideal world everyone should configure their systems 
neatly, but unfortunately we are far from ideal conditions in real life :/

I'm happy to discuss this technique but I can't really afford the 
administrative overhead I would have with users complaining about 
rejected emails..

Daniele Duca

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