kpbsd.k12.ak.us mail is handled by 30 mx3.kpbsd.k12.ak.us.
kpbsd.k12.ak.us mail is handled by 20 mail-gw.kpbsd.k12.ak.us.
kpbsd.k12.ak.us mail is handled by 40 mx4.kpbsd.k12.ak.us.
kpbsd.k12.ak.us mail is handled by 10 mx1.kpbsd.k12.ak.us.
> kpbsd.k12.ak.us mail is handled by 30 mx3.kpbsd.k12.ak.us.
> kpbsd.k12.ak.us mail is handled by 20 mail-gw.kpbsd.k12.ak.us.
> kpbsd.k12.ak.us mail is handled by 40 mx4.kpbsd.k12.ak.us.
> kpbsd.k12.ak.us mail is handled by 10 mx1.kpbsd.k12.ak.us.
servers that does not include mx4.kpbsd.k12.ak.us.
$ host -t mx kpbsd.k12.ak.us ns1.acsalaska.net.
$ host -t mx kpbsd.k12.ak.us ns2.acsalaska.net.
> servers that include mx4.kpbsd.k12.ak.us.
> > kpbsd.k12.ak.us mail is handled by 30 mx3.kpbsd.k12.ak.us.
> > kpbsd.k12.ak.us mail is handled by 20 mail-gw.kpbsd.k12.ak.us.
> > kpbsd.k12.ak.us mail is handled by 40 mx4.kpbsd.k12.ak.us.
> > kpbsd.k12.ak.us mail is handled by 10 mx1.kpbsd.k12.ak.us.
> servers that does not include mx4.kpbsd.k12.ak.us.
Sorry, I missed that it was listed in the response.
> kpbsd.k12.ak.us name server ns1.acsalaska.net.
> kpbsd.k12.ak.us name server xdns.kpbsd.k12.ak.us.
> kpbsd.k12.ak.us name server ns2.acsalaska.net.
query from NY state. Not sure what is going on.
Doing a couple of quick "digs" on the MX records, I noticed that in the "ADDITIONAL SECTION" that the ACS servers report more hosts than the kpbsd.k12.ak.us entry. Do you have access to that DNS server? I suspect the SOA may be a bit off from the others. I presume that one of the three is your "master" and the other two are slaves? I'd make sure they're all in sync and all name servers are listed in the SOA. Also, ask ACS tech support to add glue records for your servers. That could explain some of the latency.
Run the report at https://www.dnsstuff.com/tools#dnsReport|type=domain&&value=kpbsd.k12.ak.us and fix the things it notes.
kpbsd.k12.ak.us. 300 IN MX 10 mx1.kpbsd.k12.ak.us.
kpbsd.k12.ak.us. 300 IN MX 20 mail-gw.kpbsd.k12.ak.us.
kpbsd.k12.ak.us. 300 IN MX 40 mx4.kpbsd.k12.ak.us.
kpbsd.k12.ak.us. 300 IN MX 30 mx3.kpbsd.k12.ak.us.
kpbsd.k12.ak.us. 300 IN NS ns1.acsalaska.net.
kpbsd.k12.ak.us. 300 IN NS xdns.kpbsd.k12.ak.us.
kpbsd.k12.ak.us. 300 IN NS ns2.acsalaska.net.
chroot, while other domains use a non-chroot transport.