piatkow - 9:29 am on Nov 6, 2009 (gmt 0)

On the receiving side I have found that all the big webmail providers have a level of spam filtering that blocks some messages before they are offered to the recipient account.

Is the from address your Yahoo address or is it set to be from your domain name?

Can you confirm that all your own spam filters have been switched off when testing this?

While most emails go through in seconds I have known the odd one surface hours or even days later.