Can I email all my customers an attachment at once???need a fast way to send my insurance documents out to 300 customers???

Hi there, jason30.

We're currently unable to send an attachment to multiple customers in QuickBooks Online. However, you can download the attachments and manually email them to your customers. 

Here's how:

1. Click the Gear icon located in the upper right-hand corner.
2. Under Lists, click Attachments.
3. Find the attachment, and click the Download link under the Action column.

You can also check this article for more information: Attachments in QuickBooks Online.

If there's anything else you need help with QuickBooks, please let us know. Thanks.