[messo]

How is IPv6 coverage in the email provider landscape these days? I guess it would be easier to build up a decent IP reputation if it was on a "virgin" IPv6 address used only for this purpose, and not tainted by prior use etc.

IPv6-only for email is probably still a pipe dream, I guess...

[LeonM]

> I guess it would be easier to build up a decent IP reputation if it was on a "virgin" IPv6 address used only for this purpose, and not tainted by prior use etc.

IP addresses (especially IPv6) are ephemeral, email providers know that. Just about every email service has a TTL on IP reputation.

Usually, if an email is DKIM signed (and aligned) then domain reputation is used as the key indicator, the sender IP becomes less relevant in that situation.

Obviously, each implementation is different. There are no silver bullets here.

But what I'm trying to say here is: do not worry about inheriting a 'tainted' IP address. With the limited number of IPv4 addresses available, and the huge volume of spam, just about every publicly available IP would have been 'tainted' by now.

[brongondwana]

It's pretty bad - nobody is really doing it.

On the plus side, since it's all pretty fresh - you can do things like "MUST be DKIM signed from an aligned reverse DNS" on IPv6 and have a chance of it working.

[LeonM]

> It's pretty bad - nobody is really doing it.

I'm curious how you came to that conclusion.

Messo's question above made me curious, so I just did a quick query on the database of Mailhardener. >99% of email coming from Gmail is delivered over IPv6 (from ~10k samples).

This appears to be provider specific though. For example: Yahoo seems to mail exclusively over IPv4, Zoho also IPv4. Most exchange based services appear to prefer IPv6. Microsoft 365 also uses IPv6.

So your conclusion doesn't really reflect what I am seeing in our database. Obviously, we process mostly DMARC reports, so maybe regular email is more IPv4 biased to support mail services that are not IPv6 capable.