Hello,
Probably the simplest way to do this is to use Public Folders and create a separate email for each form template (XSN file). The email would have a title for the form and include a link in the body to the DBXL URL used to open the XSN, for example http://%3cserver%3e/QdabraWebService/forms/%3Cname%3E/template.xsn
You could also store a copy of your submitted InfoPath form XMLs in the public folder (by doing a double submit in your InfoPath form to DBXL and then to email) but this has the following drawbacks:
By default, there is nothing to prevent people from opening old versions. People could open old XMLs that are from previous versions of the form. You can prevent this by adding qRules and SwapDom command to your forms to force the InfoPath form to always load the database copy on open.
Versioning changes require side-by-side document types. This is related to the first bullet. Old XMLs may not open if the data source has changed. To prevent this and allow old XMLs to be opened, whenever a incompatible change is made to the form's schema, you will have to create a new doctype. You can add a convert button to the old form and use Convert feature in qRules to manually migrate old forms forward.
Another approach is to attach the XSN itself to email and have this living in the public folder (as opposed to a link). Opening an XSN from email is only supported for InfoPath forms marked as Restricted security mode. In restricted mode your forms cannot submit to a data connection (for example, DBXL). For this reason, this approach would be somewhat problematic. However, you could use a split solution technique similar to Mel's blog to submit forms to email and upload them to DBXL by someone who has installed a Domain security instance of the Restricted mode form.
Qdabra provides a Web dashboard for users to share forms in a team setting. Go to http://www.formsboard.com/ and login as anonymous, or create a new account. You can create a domain and invite your users. InfoPath form templates can be published to the domain and users can fill out the forms online. FormsBoard comes with a scalable public instance hosted on Amazon's Web Services. Encryption is used to enforce privacy. We also provide private copies of FormsBoard to companies who do not want to use the public version.
Hope this helps. Thanks!
-Prachi