How can I fill out a PDF document I received in my email and then email it to someone else?

Hi Scorpio,

What you are looking, can be done with few simple steps.

• The form that has been sent to you as an attachment- Save it locally in your system first.
• Open it with free Adobe Reader DC Adobe Acrobat Reader DC Install for all versions   or Acrobat DC (if you already have subscription).
• Use Fill & Sign tool to fill the form- Help article Using Acrobat Reader DC Fill & Sign
• Once the form is filled, save the changes Ctrl+S or File>Save or Save As.
• Compose a new mail which you would like to send to the third party> Attach form> Send.

Hope this answers your query. Let us know if you were referring to something else.

Regards,

Akanchha