[Neil]

Did you not answer entwisi's question? - is your only problem email or do you loose connection to the internet? If you are loosing connection to the internet I would look at your modem/router whatever you have and see if the ADSL (or DSL ) light is off when you loose connection. You might just have a simple wiring problem in your house. Have you correctly installed the microfilters? I have seen people with nasty phone extension leads with a filter at each end of the lead which screwed it up.