HenrysCat 0 Posted December 29, 2019 Share Posted December 29, 2019 Is there any limit or recommended limit for the number of countries that can be blocked? If I ticked them all except one for example would this slow down mail flow? Link to comment Share on other sites More sharing options...
Administrators Marcos 5,074 Posted December 29, 2019 Administrators Share Posted December 29, 2019 Please post a screen shot of the setting that you are referring to. Link to comment Share on other sites More sharing options...
HenrysCat 0 Posted December 29, 2019 Author Share Posted December 29, 2019 Link to comment Share on other sites More sharing options...
Administrators Marcos 5,074 Posted December 29, 2019 Administrators Share Posted December 29, 2019 Since the number of countries in the world is low compared to the number of IP addresses on a blacklist for instance, I don't think that even blocking all countries but one would have any adverse effect on performance. Link to comment Share on other sites More sharing options...
HenrysCat 0 Posted December 29, 2019 Author Share Posted December 29, 2019 Yes but each country block list contains every IP address allocated to that country, so that's a lot of IP addresses! This is my concern, total IPv4 addresses = 232 or 4294967296, total allocated to the UK is approx 70 million according to Ofcom, so would blocking 98.4% of all IPv4 address affect performance? I don't want to just go for it and see what happens on a production mail server. Link to comment Share on other sites More sharing options...
itman 1,659 Posted December 29, 2019 Share Posted December 29, 2019 Eset's country IP lookup is using GeoIP. This is a commercial database. I am assuming it has optimized retrieval methods for determining country associated with IP address. I did an online search here: https://www.ultratools.com/tools/geoIp and result was instantaneous. Also the data retrieved included much more than just country. Link to comment Share on other sites More sharing options...
HenrysCat 0 Posted December 29, 2019 Author Share Posted December 29, 2019 Ah so the list is external not downloaded right? so it's a lookup like a DNSBL? Link to comment Share on other sites More sharing options...
itman 1,659 Posted December 29, 2019 Share Posted December 29, 2019 (edited) 34 minutes ago, HenrysCat said: Ah so the list is external not downloaded right? Eset would have to answer this. 34 minutes ago, HenrysCat said: so it's a lookup like a DNSBL? That's my assumption. Email arrives. Origin IP address is picked up from the header. GeoIP lookup is done to determine country of origin. Eset blocked country list is searched if country of origin is on the blocked list. Edited December 29, 2019 by itman Link to comment Share on other sites More sharing options...
itman 1,659 Posted December 30, 2019 Share Posted December 30, 2019 You should also be aware of the following: Quote However, as it is trivially easy to spoof email headers, take all the results you find with a pinch of salt. https://www.makeuseof.com/tag/how-to-trace-your-emails-back-to-the-source/ Link to comment Share on other sites More sharing options...
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