Need to attach Attachments to issues when assigned

Currently when you create an issue and attach an attachment to the issue, then assign the issue to someone, the e-mail sent to the assignor does not receive the attachment.

In our environment we have various vendors that are involved in resolving issues. Because of security concerns and use of remote site we do not want to give them direct JIRA access. We prefer that when the assigned e-mail is distributed it should contain the attachment.