Postfix Multiple SMTP Relay

[contertulio]

Dear friends, I have a VPS with multiple domains hosted. Over time I was a problem with shipping to accounts 'hotmail.com'. The solution I found was to hire an SMTP service to relay e. I had to configure Postfix to have some authentication data for each domain. Here attached configuration for which you can serve:

/etc/postfix/main.cf
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwords
smtp_sasl_security_options = noanonymous
smtp_tls_security_level = may
start_tls = yes
header_size_limit = 4096000
smtp_sender_dependent_authentication = yes
sender_dependent_relayhost_maps = hash:/etc/postfix/sender_relay
relayhost =

/etc/postfix/sender_relay
[ARROBA]dominio.com [smtp.servidorsmtp.com]:25

/etc/postfix/sasl_passwords
#[smtp.servidorsmtp.com]:25 usuario:clave
[ARROBA]dominio.com usuario:clave

postmap /etc/postfix/sender_relay
postmap hash:/etc/postfix/sasl_passwords
/etc/init.d/postfix restart

This configuration works well for the relay of all emails in each domain. My question now is whether there is a Postfix configuration allowing the relay emails sent only to 'hotmail.com' for each domain. That would solve my problem, because the only emails I am having reception problems are with 'hotmail.com', others are working properly and I can send to my VPS server.

Thank you very much in advance.

[Pacopag]

What exactly was the problem with sending to hotmail account?

I had a problem where hotmail was sending all my messages to recipients' Junk folders. In my case, the problem was that my hosting company didn't set up a proper SPF record for my domains. Once the SPF was configured properly, all worked well.

If you're sure you have SPF and MX records set up correctly, then please ignore the rest of this post.

Be sure you have all your records set up correctly (SPF and reverse-DNS especially). Since you have a vps, my guess is that the hosting company doesn't automatically do this stuff for you (I don't think they have any way of knowing when you add a virtual domain to your vps, but I might be wrong). All the records are set in the zone file. Most likely, you'll have to request this from the hosting company's admins (via a support ticket or the like).

If this turns out to be your problem, then you can do away with the relay.

[contertulio]

Thank you very much for responding. To reach this step we have gone through trying to solve the problem with Hotmail no success. Everything is configured as comets and still not working.

[Pacopag]

I'm not sure how to configure postfix to use the relay only for hotmail.com recipients. But I think it's important to figure out why the problem exists ONLY for hotmail.com. What is the problem again? Is it that hotmail is sending the emails to Junk?

Make sure you're not blacklisted (Google mxtoolbox blackist) <--- I can't post urls yet.

Try sending an email without the relay to a hotmail account (in fact, send one to me at capnluca[at]hotmail[dot]com), then immediately check (and post here) the tail of /var/log/mail.log to see if there is any info that may help to determine the problem.