[renehsz]

Yeah, hosting on or at least tunneling through a commercial IP address is definitely required in order not to be flagged as spam. Personally, I chose the latter option of hosting my MTA at home but tunneling its traffic through a VPS in a datacenter. It's been working pretty well ever since, although I'm not sure it's worth the effort versus just using a cheap hosted provider.

[the_gipsy]

Is it some kind of free VPS?

[layer8]

VPS are generally paid, but it's only $5 or less a month.