You can add attachments/files to outgoing correspondence from Buildxact. These files will appear to the receiver as attachments to view/download.
Once the combined file size reaches 10mb, the files will then be embedded in the email as links to the attachments, with a notification that the link will expire within 7 days.
If you are sending from an integrated email account, the size limit will be 25mb before the attachments will be sent as links rather than attachments.
It is not possible to extend this expiration time limit.