I use a contact form for emails and advise all clients to add webpage@mysite.com into their contacts list so that emails are not dismissed as spam.

Yesterday, however, one customer who claims she has done this but that it is hit and miss as to whether emails get through - some do some don't. (Two people have sent her emails and these have not got through - one person then resent an email and it DID get through and emails she sends herself via the contact form do get through.)

She uses hotmail; we use Streamline as a host and they claim to do NO spam filtering and just send every email on to hotmail. There are no emails in her route directory at Streamline.

Has anyone met this type of thing before? Any suggestions???? IS there anything I can do to make sure 100% emails get through?

I'm a bit worried right now as this makes our website contact form unreliable?

Hotmail is infamous for not letting emails through, I would suggest to add a comment next to the email textbox, saying that Hotmail will not receive your emails.
That's the only thing I could think of...