How does the file attachments feature work?
The same as adding extra fields.
Go to the contact form settings page to edit a form.
Click on Advanced Options.
Type a label for your extra field attachment such as "Attach photo:"
Select the field type "attachment", check the "required" box of you
want it to be required.
You can add more than one attachment extra field.
Below the extra field settings you will find the "Attached files
acceptable types:" setting.
Set the acceptable file types for the file attachment feature.
Any file type not on this list will be rejected.
Separate each file type with a comma character.
Also set the "Attached files maximum size allowed:" setting.
Set the acceptable maximum file size for the file attachment feature.
example: 1mb equals one Megabyte, 1kb equals one Kilobyte
Note: Maximum size is limited to available server resources and
various PHP settings.
Very few servers will accept more than 2mb. Sizes under 1mb will
usually have best results.
examples: 500kb, 800kb, 1mb, 1.5mb, 2mb
Note: Don't set any higher than you actually need. If you set the value higher than your server can handle, users
will have problems uploading big files. The form can time out and may
not even show an error. 1mb or less is highly recommended.