An email address does contain at least one dot; Take Pete@Gekko-Software.nl Some organizations, like mine, also use dots in the first parts; like Pete.van.Ooijen@Gekko-Software.nl Imho this makes sense, the dots separate the parts of my full name. But a lot of sites, including FI parts of MSDN, do not accept such an address; it's considered ill-formatted. Not very user-friendly, especially when the messages returned are pretty vague.