Whenever our mail server sends emails to our customers, it mostly ends up in their junk folder as hotmail considers it as spam.

Is there any way you can validate your domain with hotmail or in any other way solve this? This issue also happens to certain ISPs web servers as well.

We use MailEnable/Win2k3

Check whether your mailserverIP is listed under any spam database or check whether your domain has RDNS setup.

If you don't have RDNS then it could be one of the reason for this occurrence.

How are you sending mail Kendan - PHP scripts or the like? Like besty writes, check spews.org to see if your IP is blacklisted. Past that, ensure that all users are using authenticated SMTP, and that your domain has an SPF record (which a select few ISPs use to check mail authenticity). You can visit http://dnsreport.com/ for a quick check as well!

Hope this helps!
Alex

I think it might be that i'm lacking a SBF record. I've tried configurating one, but not sure which one that is the zone file.
Is that the file named just like my domain, placed in the /var folder?

I tried adding the 4 lines below, but that just messed most things when i did run the DNS report test all over.
If you run BIND

Paste this into your zone file: xxxxxxxx.net. IN TXT "v=spf1 a mx ~all"When a mail server sends a bounce message, it uses a null MAIL FROM: <>, and a HELO address that's supposed to be its own name. SPF will still operate, but in "degraded mode" by using the HELO domain name instead. Because this wizard can't tell which name your mail server uses in its HELO command, it lists all possible names, so there may be multiple lines shown below. If you know which hostname your mail server uses in its HELO command, you should pick out the appropriate entries and ignore the rest.
So this should also appear in DNS. You may or may not be in charge of the DNS for these entries; if you are, add them.
mail.xxxxx.net. IN TXT "v=spf1 a -all"smtp.xxxxx.net. IN TXT "v=spf1 a -all"www.xxxxx.net. IN TXT "v=spf1 a -all"

SPF records wouldn't cause all ISPs to block mail, only a select few use SPF. There's an SPF record wizard here though:

http://www.microsoft.com/mscorp/safety/content/technologies/senderid/wizard/

What did DNSReport.com have to say about your domain's mail servers? What about spews.org?

You can create your SPF record using the wizard at http://www.openspf.org/

Once you add this to your DNS entries your mail should get through to hotmail users (or at least have a much better chance) as MS does recognise SPF records (http://www.microsoft.com/presspass/press/2005/mar05/03-02SIDFPR.mspx).

You can also test your setup: send an e-mail message to check-auth@verifier.port25.com. In return, you will receive a reply containing an analysis of the authentication status of the message you sent.

Once you have done that, MS recommends you mail them the details to they can update their cache DBs: Send an e-mail with your domain name in the body of the message (for example, mydomain.com) to senderid@microsoft.com. If you have multiple domain names, please list each domain on a separate line in the body of the message.

To get assistance to add your SPF entry into the DNS, you need to talk to whoever runs your DNS server. Just create a new TXT entry alongside the A record.

Don't feel back, when Earthlink sends me message (not phished) their spam filter labels it as spam and junks it. Go figure.