domain does not resolve

[DH]

I've been trying to figure out a problem with some of my alias domain names
for a while and just can't figure it out.  When I send email with a FROM
address of these domains, I get bounces saying the following:

.... while talking to mailin1.accesscomm.ca.:
>>> MAIL From:<owner-johnyoung at johnwyoung.org> SIZE=1825
<<< 451 4.1.8 Domain of sender address owner-johnyoung at johnwyoung.org does
not resolve

I get the following using dig:

]# dig johnwyoung.org mx

; <<>> DiG 9.2.1 <<>> johnwyoung.org mx
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 15560
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2

;; QUESTION SECTION:
;johnwyoung.org.                        IN      MX

;; ANSWER SECTION:
johnwyoung.org.         60      IN      MX      10 gemini2.johnwyoung.org.

;; AUTHORITY SECTION:
johnwyoung.org.         60      IN      NS      columbia.johnwyoung.org.
johnwyoung.org.         60      IN      NS      gemini2.johnwyoung.org.

;; ADDITIONAL SECTION:
gemini2.johnwyoung.org. 60      IN      A       205.165.189.182
columbia.johnwyoung.org. 60     IN      A       205.165.189.130

;; Query time: 13 msec
;; SERVER: 205.165.189.130#53(205.165.189.130)
;; WHEN: Thu Dec 16 11:18:53 2004
;; MSG SIZE  rcvd: 125

My DNS entry for this domain looks like:

@       IN     SOA     columbia.navarrocollege.edu.
root.columbia.navarrocollege
..edu. (
                2004080301      ; Serial Number YYMMDDxxx
                900             ; Refresh 2dary
                900             ; 2dary retries after ..
                604800          ; 2dary says primary is dead after ..
                60 )            ; TTL in cache - 30 min
                                IN      NS      columbia
                                IN      NS      gemini2
johnwyoung.org.                 IN      MX      10 gemini2
johnwyoung.org.                 IN      A       205.165.189.178
sts                             IN      A       205.165.189.178
www                             IN      CNAME   sts
columbia                        IN      A       205.165.189.130
dns                             IN      CNAME   columbia
wormhole                        IN      CNAME   columbia
localhost                       IN      A       127.0.0.1
gemini2                         IN      A       205.165.189.182
mail                            IN      CNAME   gemini2
pop                             IN      CNAME   gemini2
dns2                            IN      CNAME   gemini2
dilbert                         IN      CNAME   gemini2

Can anyone help me solve this issue?