We have over 5000 mailboxes on a single domain and would like to have the facility to allow any one of these to send an email to all or a selection via a webpage form.
This is an internal email only to those listed in the domain. The list of member of the domain are already in a database on the website and although they all have pop access to their mailbox due to privacy they do not have access to the membership list.
We also cannot do this by lists as there are too many variables which would create too many lists. We need to do this on the fly with the results of a database search creating the mailing list which with the message needs to be sent to the mailenable server.
The members are worldwide and can be registered with many parameters like location, expertise, department, social group, network group, etc,etc.
Prefer php coding but also use asp.