Mail Server for SugarCRM

[fmdn]

I'm trying to setup a mail server to use with sugarcrm. I'm not a mail expert. My setup is a XAMPP installation on a windows server VPS. I have a domain , and the IP address of the VPS I'm using is already defined as a valid IP for sending mails from my domain - I added the SPF record. I intend to use it for sending a Newsletter via sugarcrm. I want the emails to be delivered directly by my server and not using a smart host (end-to-end SMTP).
I already tried a couple of mail servers: Mercury Mail server, hMail server and Mail Enable Standard Edition.

None of them worked out of the box. I followed a couple of tutorials to configure them. I don't want them to be open relays, so in all of them I'm allowing mails to be sent when the request comes from localhost.

I'm able of sending emails using a php script using both Mercury Mail server and Mail Enable, but not with hMail. Surprisingly, sending mails from sugar it's been a headache. I was expecting that configuring sugar for using sendmail would suffice, but that way messages don't even seem to reach the mail server. So I configured for using SMTP, point it to 127.0.0.1 and I see the mail entering the mail server but either they're not delivered or at least some are not delivered. Sending via php script to Gmail works, but not via sugar...

Why am I able of sending mails via my php script but not through sugar? Shouldn't this be quite straightforward after achieving that the php mail function works? What Mail Server for windows would you recommend? I'd like one that would be easy to install and to administrate. I'd like to be able of easily monitor the outbound messages status. Anyone experienced with any of these mail servers could point me out where to look? I'm a bit lost here, could someone point me to the configuration variables on the mail server that I need to address.

Thanks

[fmdn]

Looking at the Mercury Mail server logs I narrowed one problem.
When Mercury tries to deliver one of the emails I get this:

MAIL FROM:<>
550 Access denied - Invalid HELO name (See RFC2821 4.1.1.1)

One of the mail addresses I'm testing this with belongs to my domain. So this might be some conflict because I'm sending mai to my mx serverl from a server that is allowed to send mail on the behalf of my domain mx server. Might this be the reason that my mx server is rejecting this?

By reading RFC2821 4.1.1.1, it seems to me that Mercury "forgot" to issue the EHLO command. And why is the from-address in blank? It's correct in the rest of the emails of the target lists.