10.6 Email-Server/Postfix Helo command rejected - local SMTP clients won't use FQDN

Question

Hi,
I set up a 10.6 server as mail-server which works (more or less) fine. I can send and receive internal and external Emails from various Macs with mail.app and Windows-Boxes with Thunderbird. However, some clients will be rejected due to wrong Helo strings
e.g. a Windows-Box using Outlook express
server postfix/smtpd[73194]: NOQUEUE: reject: RCPT from winbox.intranet.example.com[192.168.2.21]: 504 5.5.2 <winbox>: Helo command rejected: need fully-qualified hostname; from=<[email protected]> to=<[email protected]> proto=ESMTP helo=<winbox>
similar happens with my router sending status-Emails (replace "winbox" with "router")
finally my stand-alone-fax-machine uses it's ip-address as helo-string (helo=<192.168.2.10>, similar error)
For now I've commented out
smtpd_helo_restrictions = reject_invalid_helo_hostname
#reject_non_fqdn_helo_hostname
which makes things work. But that's not the right way, I guess, moreover since this entry is "fixed" by Server-Admin ever now and then.
Does this problem arise from misconfigured boxes or a misconfigured OSX-Server? Hope the latter since there're no options to change this in my router nor my fax-machine...
Thanks

Answer 1

Try this.
     Symptoms   Users who use Microsoft Outlook as their email client and whoconnect to an email server running on Mac OS X Server v10.6 may not beable to send mail. The following (or similar) alert is returned toOutlook clients:    The message could not be sent becauseone of the recipients was rejected by the server. The rejected emailaddress was "[email protected]" is subject "example", account:"mail.example.com" , server "mail.example.com", protocol: SMTP, serverresponse: "504 5.5.2 < hostname > : Helo command rejected: needfully qualified host name", port: 25, secure (SSL): no, server error:504, error number: 0x800CCC79.      Products Affected   Mac OS X Server 10.6        Resolution    In Mac OS X Server v10.6, Postfix is configuredto require a fully qualified hostname from SMTP clients. This settingis configurable and the restriction can be removed, however anymodification of a security-related setting should be evaluated prior tomaking the change.   Once you have evaluated the change, you can use the following steps to implement it:   Note: Before proceeding, back up the /etc/postfix/main.cf file as a precaution.  
In /etc/postfix/main.cf, locate the smtpd_helo_restrictions setting
Remove "reject_non_fqdn_helo_hostname" from the list of settings.
Restart the Mail service.