Bug#949335: exim4: Does not allow relay from IPv6 localhost like for IPv4

[Andreas Metzler]

On 2020-01-20 David Lee Lambert <davidl at lmert.com> wrote:
> Package: exim4
> Version: 4.92-8+deb10u3
> Severity: normal
> Tags: ipv6

> Dear Maintainer,

> I was getting a "Relay not permitted" message from Thunderbird trying
> to send e-mail.

> The immediate workaround was to change the "Server Name:" in Server
> Settings from "localhost" to "127.0.0.1". However, the manpage says,
> and said in squeeze [1],

> > dc_relay_nets
> >    A list of machines for which we serve as smarthost. _Please note that 127.0.0.1 and ::1 are always permitted to relay since /usr/lib/sendmail is available anyway and relay control doesn't make sense here._ Sets macro MAIN_RELAY_NETS

> (I actually had "...; 127.0.0.1/8; [::1]/128; ..." in dc_relay_nets, but
> taking those entries out didn't seem to make any difference.)

> Testing with "telnet", IPv4 localhost is allowed to relay, IPv6 localhost isn't:
[...]

Compare the results of

swaks --pipe '/usr/sbin/exim4 -bh ::1' -f test1 at lmert.com -t john.doe at example.net -q rcpt

and

swaks --pipe '/usr/sbin/exim4 -bh 127.0.01' -f test1 at lmert.com -t john.doe at example.net -q rcpt

cu Andreas
-- 
`What a good friend you are to him, Dr. Maturin. His other friends are
so grateful to you.'
`I sew his ears on from time to time, sure'