As a lot of ppl found out, sending a mail to chello.nl is hard to do with your own MTA on a consumer broad-band connection. The consumer ranges are blocked by Chello/UPC

But we can hack it... al you need is access to a non-blocked MTA (i.e. smtp.xs4all.nl)... And I use sendmail as a MTA... and sendmail got the feature
mailertable With this feature you can override the mx-records out of the DNS-server... So I added the next line:
chello.nl smtp:smtp.xs4all.nlAnd now I can deliver mail to chello.nl via smtp.xs4all.nl.