Need doc clarifications on the send method parameters

[dgoldenberg-audiomack]

Could someone provide some insight on the below pls?

(Looking at the project doc here)

• use_sandbox (bool) – Flag must be set to use sandbox domain instead of verified sending domain. Limited to a lifetime of 50 transmissions with this domain. - I'm not clear on the usage of this flag. We just want to send some emails on behalf of something like "data@acme.com". Can we just set this flag to False? When might we want to set it to True?
• Attachments. So this is a list of dictionaries. Does this support the s3 protocol so as to be able to pass in AWS S3 based filepaths? If not, should we just download the files locally, base64-encode them, and attach the dicts?
• For the below sample for attachment handling:

dict(
    type='application/pdf',
    name='document.pdf',
    filename='/full/path/to/document.pdf'
)

Are all the 3 parts of this mandatory? Do we need to supply the MIME type? the filename? The filename is easy to supply; mostly wondering if the MIME type is mandatory.

• Campaign. Is there any benefit to supplying this value? Is this the campaign name from the config?