Virtualmin/Webmin, Postfix, Virtual server.. problems on CentOS5

[Devil]

Hello,

I installed Virtualmin using their free GPL'd install script on a fresh install of CentOS5.
Currently, this server all it needs to do is serve http and send out signup/confirmation/activation emails generated by PHP scripts.

So, using Virtualmin, I added a virtual server called domain.com. Domain.com has http being served, ftp, mysql is also working, but mail is being a problem. Virtualmin installs Postfix as the mailer.

domain.com's email is being handled by GoDaddy. But I just want the scripts to be able to send out all the generated emails from the CentOS server/postfix.

For example, the domain's admin should be able to send out whatever email addr he wants:
I want it to go out like script@domain.com, instead of apache@myserver.hostname.com

I tested it out, I sent emails using Usermin to @msn (failed 4 out of 6 times), @gmail (all success), @domain1 and @domain2 (handled by GoDaddy's email again, where all was successful to go to @domain1, but 100% failure on @domain2)
The custom domains have no spam/junk controls.


Now, if I want the emails to go with 99% success rate, what do I need to change in postfix configuration?

Please, please help.

[falko]

You can set the correct sender address in the $additional_headers in PHP's mail() function. See http://es.php.net/manual/en/function.mail.php

If you have an SPF record for your domains, make sure that the sending server is included there.

[Devil]

You can set the correct sender address in the $additional_headers in PHP's mail() function. See http://es.php.net/manual/en/function.mail.php

If you have an SPF record for your domains, make sure that the sending server is included there.

That's the thing, I don't know anything about setting up an SPF for my mail server so mail going out from all the virtual domains hosted on the server do not get classified as spam.

[Devil]

Also, I guess I'll need to do stuff for Hotmail.
As currently, Gmail takes my email everytime. Yahoo takes it 9 out of 10 times, and would give an error sometime:

421 Message from (63.xx.xx.xx) temporarily deferred - 4.16.50. Please refer to http://help.yahoo.com/help/us/mail/defer/defer-06.html)

And when I send email to hotmail, the mail server doesn't get any errors.. but the mail doesn't arrive in hotmail/msn's inbox, nor the junk folder.

What needs to be done?

[falko]

Are you managing the DNS records for your domain yourself, or who does it?

[Devil]

Are you managing the DNS records for your domain yourself, or who does it?

DNS is hosted at GoDaddy and I control it. I even added an SPF record for @
I hear the Yahoo/Gmail rely on SPF, but even before I put on SPF they would rcv the emails.

Even now, Yahoo/Gmail work properly. Except sometimes I get that error from Yahoo. Currently in talks with Yahoo to get us whitelisted.

Hotmail is the only one that hasn't worked even once. No error on my side, but no email in the hotmail inbox/junk folder.

[falko]

You can use this wizard: http://old.openspf.org/wizard.htm to find out how your SPF record should look.
Compare this to the output of
dig txt yourdomain.com