Send only one e-mail to many recipients (all recipients in one to-header)

If a list of recipients for an announcement mail is specified by multiple <toAddress>s in the <toAddresses>-tag, like this:

<toAddresses>
    <toAddress implementation="java.lang.String">recipient1@mydomain.net</toAddress>
    <toAddress implementation="java.lang.String">recipient2@mydomain.net</toAddress>
</toAddresses>

then 2 e-mails will be sent, one to recipient1@mydomain.net, and one to recipient2@mydomain.net.

To have all the recipients for the announcement visible in the mail and to enable reply-to-all (what we use for our release-to-production process) it would be necessary to send an e-mail with all the recipients listed in the to-header of the mail (comma-seperatored), i.e. with a header like this:

To: recipient1@mydomain.net, recipient1@mydomain.net