Sendmail- Between Two Hosts

on a sendmail issue that I'm seeing, to which both my hosts are saying "nothing wrong at this end".

Some background:
A few months back, I moved my XXX.com from SLHost to another host. But I forgot to remove the account in WHM at SLHost until a day or two ago.

Since then, mails generated by the server (eg, from a PHP script, or the cron messages) are not getting to the XXX.com account - they're just sitting in the mail queue. I can use POP3 to send mails from accounts on SLHost to XX.com without any problems.

Some diagnostics:

MAIL QUEUE OUTPUT FROM SLHOST.COM

Message 1Iju1W-0001a9-G6 is not frozen
delivering 1Iju1W-0001a9-G6
Connecting to XXX.com [209.51.132.1]:25 ... connected
SMTP<< 220-bee.nswebhost.com ESMTP Exim 4.68 #1 Tue, 23 Oct 2007 08:01:17 -0500
220-We do not authorize the use of this system to transport unsolicited,
220 and/or bulk e-mail.
SMTP>> EHLO server.resource-directory.info
SMTP<< 250-bee.nswebhost.com Hello server.resource-directory.info [207.210.221.149]
250-SIZE 52428800
250-PIPELINING
250-AUTH PLAIN LOGIN
250-STARTTLS
250 HELP
SMTP>> STARTTLS
SMTP<< 220 TLS go ahead
SMTP>> EHLO server.resource-directory.info
SMTP<< 250-bee.nswebhost.com Hello server.resource-directory.info [207.210.221.149]
250-SIZE 52428800
250-PIPELINING
250-AUTH PLAIN LOGIN
250 HELP
SMTP>> MAIL FROM:<nobody@server.resource-directory.info> SIZE=2117
SMTP>> RCPT TO:<subtest3@XXX.com>
SMTP>> DATA
SMTP<< 250 OK
SMTP<< 451 Temporary local problem - please try later
SMTP<< 503-All RCPT commands were rejected with this error:
503-Temporary local problem - please try later
503 Valid RCPT command must precede DATA
SMTP>> QUIT
LOG: MAIN
== subtest3@XXX.com R=lookuphost T=remote_smtp defer (-44): SMTP error from remote mail server after RCPT TO:<subtest3@XXX.com>: host XXX.com [209.51.132.1]: 451 Temporary local problem - please try later

DIG MX OUTPUT FROM SLHOST:
; <<>> DiG 9.2.4 <<>> mx XXX.com
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 3132
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 1

;; QUESTION SECTION:
;XXX.com. IN MX

;; ANSWER SECTION:
XXX.com. 4116 IN MX 0 XXX.com.

;; AUTHORITY SECTION:
XXX.com. 76116 IN NS ns2-bee.nswebhost.com.
XXX.com. 76116 IN NS ns1-bee.nswebhost.com.

;; ADDITIONAL SECTION:
XXX.com. 4116 IN A 209.51.132.1

;; Query time: 1 msec
;; SERVER: 207.210.221.149#53(207.210.221.149)
;; WHEN: Tue Oct 23 08:03:33 2007
;; MSG SIZE rcvd: 123

So, that seems to be OK - the server at SLHost recognises that mail should go to the IP listed for the new account.

DNSREPORT.COM WARNINGS:
WARNSOA REFRESH valueWARNING: Your SOA REFRESH interval is : 86400 seconds. This seems high. You should consider decreasing this value to about 3600-7200 seconds (or higher, if using DNS NOTIFY). RFC1912 2.2 recommends a value between 1200 to 43200 seconds (20 minutes to 12 hours, with the longer time periods used for very slow Internet connections), and if you are using DNS NOTIFY the refresh value is not as important (RIPE recommend 86400 seconds if using DNS NOTIFY). This value determines how often secondary/slave nameservers check with the master for updates. A value that is too high will cause DNS changes to be in limbo for a long time.

------

WARNSOA EXPIRE valueWARNING: Your SOA EXPIRE time is : 3600000 seconds. This seems a bit high. You should consider decreasing this value to about 1209600 to 2419200 seconds (2 to 4 weeks). RFC1912 suggests 2-4 weeks. This is how long a secondary/slave nameserver will wait before considering its DNS data stale if it can't reach the primary nameserver.

--------

FAILReverse DNS entries for MX recordsERROR: The IP of one or more of your mail server(s) have no reverse DNS (PTR) entries/* (if you see "Timeout" below, it may mean that your DNS servers did not respond fast enough)*/. RFC1912 2.1 says you should have a reverse DNS for all your mail servers. It is strongly urged that you have them, as many mailservers will not accept mail from mailservers with no reverse DNS entry. You can double-check using the 'Reverse DNS Lookup' tool at the DNSstuff site if you recently changed your reverse DNS entry (it contacts your servers in real time; the reverse DNS lookups in the DNS report use our local caching DNS server). The problem MX records are:
1.132.51.209.in-addr.arpa [No reverse DNS entry (rcode: 3 ancount: 0) (check it)]

-------

WARNMail server host name in greetingWARNING: One or more of your mailservers is claiming to be a host other than what it really is (the SMTP greeting should be a 3-digit code, followed by a space or a dash, then the host name). If your mailserver sends out E-mail using this domain in its EHLO or HELO, your E-mail might get blocked by anti-spam software. This is also a technical violation of RFC821 4.3 (and RFC2821 4.3.1). Note that the hostname given in the SMTP greeting should have an A record pointing back to the same server. Note that this one test may use a cached DNS record.

XXX.com claims to be host bee.nswebhost.com [but that host is at 64.22.69.42 (may be cached), not 209.51.132.1].