I'm trying to get to the bottom of why emails sent from my mail server invariably (but not always) returns the following message:
MailEnable: Message delivery has been delayed.
Message is waiting at home for delivery to a.mx.mail.yahoo.com.
The message will be retried for another 30 hours.
Reason: Mail Server for yahoo.com could not accept your email at this time. MailEnable will keep trying to deliver this message and will notify you of any progress.
The remote mail server returned the error:
421 Message temporarily deferred - 4.16.51. Please refer to http://help.yahoo.com/help/us/mail/defer/defer-06.html
Needless to say I've contacted Yahoo several times with only automated responses.
I really need a solution as I have a client with a Yahoo address who receives email copies of form submission made from the site.
My mail server is running on a VPS at webfusion on the same server and IP as the main website. I'm assuming that there is some configuration issue which is causing Yahoo to score my emails as spam. I do not bulk mail or carry out any activity that might make Yahoo greylist my IP. What I'm hoping for is some advice an a way to check the integrity of the mail servers set up to see if I can isolate Yahoo's problem with it.
So far I've done the followig:
1. I've checked and the mail server IP does not appear on any spam blacklists
2. Using information in a previos post I telnet'd the Yahoo mail records and I got a 250 OK response from the A record but a 421 response (as above) from the B record. Perhaps this is why the issue is intermittent.
3. If I run a DNS test using www.intodns.com
it warns me that my name servers are running on the same IP as my domain and that both NS records point to the same IP, both of which are true. Do you think this may cause Yahoo some problems?
4. The reverse DNS lookup is wvps[my IP address].vps.webfusion.co.
uk rather than "mail.[my domain]". I'm assuming that this is a function of the VPS and controlled by webfusion so I may not be able to change it. Do you think that Yahoo may have a problem with this?
5. The only other issue listed by www.intodns.com
is "Your SOA serial number is: 1237299768. That is NOT OK". To be honest I've no idea of the purpose of an SOA record or why the serial number should be a problem.
The mail does usually (but not always) arrive at Yahoo and if it does is usually classified as Spam.
I'd be grateful for any suggestions on how to track this down.