Not getting all my mail with BIND 4.9.7 on NT

[King Wilder]

I recently upgraded my NT box to BIND 4.9.7 from MS DNS.  I think this was a
good move.  I'm fairly new to DNS but I think I understand the basics.

I'm a web developer who is now hosting clients.  Sites work ok, but my mail
for my site only seems to be screwing up slightly.  I get about 15 to 20
e-mails a day but I am also getting calls from clients asking why I haven't
responded to their e-mails.  This is because I haven't gotten them.

I'm running my own primary DNS and the ISP I'm colocating with is running my
secondary.

As far as I can see this is all correct.

@        IN SOA    ns.mydomain.com. postmaster.mydomain.com. (
        1999101513   ; serial  [yyyyMMddNN]
             21600   ; refresh [6h]
              3600   ; retry   [1h]
            691200   ; expire  [8d]
             86400)  ; minimum [1d]

 IN NS ns.mydomain.com.

ns   IN  A 209.24.22.19
web   IN  A 209.24.22.169
localhost IN  A 127.0.0.1


ns   IN MX 10 ns.mydomain.com.


www  IN CNAME web.mydomain.com.
ftp  IN CNAME web.mydomain.com.
@  IN A 209.24.22.169

Any ideas?  Anything is appreciated.

Thanks,

King Wilder