The country where the web serverhosting your website is located. Location plays a role in terms of SEO. If your website is hosted (i.e. the physical server containing your website) in the USA and your target market is located in South Africa this can have a negative effect on your ranking. The degree to which this play a role is unknown as the search engine companies (such as Google) do not make public the algorithms (methods) used to determine ranking.
Location does not play a major role in terms of e-mail hosting. It is worth noting that whilst this does play a role in terms of speed the impact is very small and almost unnoticeable.