Newbie: Slow scheduling?

[Dani Pardo <dani@minerva.enpl.es>]

 Hi, I'm using Zmailer 2.99.50-s19, and everything seems to work, but I've
noticed that it's a bit slow:

Jun 29 09:36:00 calix router[2257]: S.rS5RM104048:
from=<dani@calix.enpl.es>, rrelay=dani@localhost size=327, nrcpts=1,
msgid=<19990629093552.A2361@calix.enpl.es>
Jun 29 09:36:10 calix mailbox[2367]: S.rS5RM104048: to=<dani>,
delay=00:00:18, xdelay=00:00:00, mailer=local, stat=ok3 Ok

 I don't understand those 18 seconds of delay (sendmail usually gives 0-1
seconds..). This delay goes from 7 to 30 seconds.. I'm I doing something
wrong? I'm using bind-8.1.1 as the nameserver. And I'm using zmailer in a
Sparc Ultra 1 and a PPro 200 (same results).
 Reply also by email please (I'm not subscribed to the list). Notice also,
that I'm a bit lame at SMTP :))
 Thanks in advance,

---
Dani Pardo, dani@enpl.es
Enplater S.A