receive some email delay / delay from topic

[fonnnnnn]

i use mantis 1.2.3 with centos 5.4

i installed mantis three month ago with no problem with email. but last week i found that some email sent to recipient delay 3 days.

i checked in database in table "mantis_email_table" and it has details here.

i checked with exchange log and mailgateway and found that exchange receive log from my mantis delay too.

for example

issue A create on 14.00 today :
the email should sent to 4 recipient immediately . But i found 2 email in database and 2 email was sent.

2 day later (when the issue have some changed !!) the 4 new email and the 2 delay email was sent to recipient with new timestamp.

What i can do to check my problem with email ? I dont know the problem comes from my mantis or my company email system (the emails consist of my domain + hotmail + gmail + the other domain)

plz help.