Email woes

[LoisWakeman]

Having finally got my internet access back, I now have an annoying problem with emails. Messages from just one of my colleagues (as far as I know - others may not have yelled so loud!) go missing randomly - she can ask for and get a delivery receipt, but the message disappears silently from the server and I never see it.

The web host has not been especially helpful, saying that it's probably my spam filters - but as they are only set to move messages to the junk folder and are always reviewed before I delete them, this is just silly.

She is in my trusted contacts list.

Any tips for where to look/what to try next? I don't have access to the mail server logs unfortunately.