manually expiring cached dns entries on nameservers

[Rein Petersen]

Hi All,
I'm trying to assist a friend who has incorrectly updated his mx entries for his site. As people have been unsuccessfully trying to send mail from various networks, new cached entries that are incorrect are going to continue to misroute mail until they expire (an unfortunately long time). I am hoping that there may be a way for me to update caching dns servers on other networks - or at least tell them to drop whatever cached records they are holding...

Is this possible and if so, how?

Thanks in advance,

Rein