Is greylisting would effect all domains that serve the same email service?

For example:

Google is own @gmail.com and @googlemail.com for their email service

FastMail have multi domains, you can check it from here

In a nother words, Multi domains that have the same MX and IPs which belongs to same email service provider.

If my server got a greylisting from @domain1.tld while i'm trying to send an email to it, is that mean i got greylisting on @all_other_domains.tld of the same service?

Thank you.

  • 2
    Likely yes. But it’s impossible to account for all the different scenarios and providers. – Appleoddity Jan 1 at 16:42
  • @Appleoddity +1 thank you! – user2203703 Jan 9 at 14:47

I would assume that greylisting is configured on a server level and affects all mail domains hosted on those servers. However, it is certainly possible to disable/enable greylisting based on the recipient domain, so you can't really know without trying.

Also, note that greylisting works using a lookup table with a key composed of: - client ip (sending mail server) - sender address - recipient address

So, if you got greylisted while sending a mail to a certain recipient, you will only not again get greylisted for mails sent to the same recipient. Some greylisting implementations (such as postgrey), try to be a bit smart about it and will after some successfully delievered greylisted mails whitelist the client completely, so that no further greylisting will be done.

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