How to : Save attachment on Horde Sent item
Note :
Horde Webmail do not save attachments in Sent email.
If you would like to save all the attachment in Sent email.
You need to update your setting with below steps :
1) Login to your Horde Webmail
2) Find Preference > Mail
3) Click "Sent Mail"
4) Change "Do not save attachments" to "Save attachments".
5) Now your successfully update your setting to save all the attachment in Sent email.