Soldato
I'd go with a hosted solution first
You will likely be paying less than £10 a month per mailbox but this gives you the following:
1) Opportunity to see if you need the technology or not without shelling out for SBS/Exchange
2) No need to worry about the server side of things, patching, maintenance, implementation, backups etc.
3) Spam filtering for messages at a domain level
4) Exchange features to support a growing business - you can use mailbox/calendar sharing, delegation for sending on behalf as users, public folders for sharing addresses. You will also get the ability to configure global contacts and distribution lists. Other features such as Out of Office etc.
5) You will be able to expand the number of users simply
You will likely be paying less than £10 a month per mailbox but this gives you the following:
1) Opportunity to see if you need the technology or not without shelling out for SBS/Exchange
2) No need to worry about the server side of things, patching, maintenance, implementation, backups etc.
3) Spam filtering for messages at a domain level
4) Exchange features to support a growing business - you can use mailbox/calendar sharing, delegation for sending on behalf as users, public folders for sharing addresses. You will also get the ability to configure global contacts and distribution lists. Other features such as Out of Office etc.
5) You will be able to expand the number of users simply