Hello Matus, and others,
Op 11-04-22 om 16:17 schreef Matus UHLAR - fantomas:
On 11.04.22 15:38, Richard Rasker wrote:
I've been using Postfix for many years without significant problems.
However, due to a forced change in ISP, I can no longer have a
correct PTR record pointing to mail.linetec.nl, causing a lot of
ISP's to reject e-mail from my server.
Reverse DNS for my IP address now points to the ISP's generic name
77-172-184-9.fixed.kpn.net
Could I solve this by setting smtp_helo_name in main.cf to
77-172-184-9.fixed.kpn.net ? Or is this a bad idea?
this will not help your problem. many ISPs will reject not because
helo name but because of your reverse DNS format.
ask your ISP to change reverse DNS for your IP to mail.linetec.nl when
possible.
if not possible, you'll need external smtp server, or different ISP.
Thank you for your swift answers!
Unfortunately, my new ISP says they can only do that for business
accounts, which would cost me several dozen euros extra per month. I'm
pretty angry about this, because I explicitly chose my previous ISP
(XS4All) for their excellent technical features & support -- and they
did not warn me that their take-over by the current ISP (KPN) could have
consequences like this.
After contacting the helpdesk (30 minutes waiting ...), I was told that
I could configure Postfix to use a mail relay of the previous ISP,
changing my MX record accordingly (smtp.xs4all.nl), but that doesn't
appear to work properly either. But maybe I did something wrong -- I
have no experience with relay servers yet.
This is what I added to my main.cfg, based on what I found on the Internet:
relayhost = smtp.xs4all.nl
... [further down]
#Enable Authentication
smtp_sasl_auth_enable = yes
#Set Username and Password
smtp_sasl_password_maps = static:Chosen-Username:Chosen-Password
smtp_sasl_security_options = noanonymous
#Enable TLS Encryption
smtp_tls_security_level = encrypt
header_size_limit = 4096000
#Enable CA Certificates
smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt
When restarting Postfix, no mail at all seems to be getting through any
more -- and how should this solve the reverse DNS problem? Because
smtp.xs4all.nl has IP address 195.121.65.191, but this IP address again
does not point back to smtp.xs4all.nl ...
I then tried the same with mx.kpnmail.nl -- which is a mail host of my
current ISP, which indeed has a valid PTR record, but still no mail
appears to get through. So in order to post here, I changed things back
for the time being. Perhaps I made a mistake in main.cf?
Thanks again, best regards,
Richard
