When I send an attachment in an email, it gets delivered as a link to the file.
By default, Horde in Parallels Plesk Panel (Plesk) 11.5 sends attachments as links according to its configuration. The case has been submitted to the Plesk Service Team as an internal issue with the ID TP-143316. The fix is planned to be included in a future Plesk update.
To disable this option, set link_attachments to
$conf['compose']['link_attachments'] = false;