On 16 Sep 2019, at 9:17, Paul van der Vlis wrote:
I guess only the big
providers will have different servers for inbound and outbound email,
and you can make a list of them.
Bad guess.
Many business email systems are architected this way for security
purposes (e.g. Exchange is fine for sending mail out but you really
don't want it accepting email from the Internet directly...) This is
especially common with older businesses who got generous IPv4
allocations decades ago, however I have worked with mail systems serving
less than 500 employee-users of companies with /29 allocations that have
mail going out from a shared NAT address but coming in via a dedicated
IP.
--
Bill Cole
b...@scconsult.com or billc...@apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
