That's tricky, since Airtable doesn't support "global fields".
You would need to create a completely separate table (you could call this table "Attachments" or "Utility Table" or "Admin Table" or "Global Table"), and create ONE RECORD in that table to hold your attachment.
Then, for all new records that get created in your base, you will need to have an automation that automatically LINKS the new record to that ONE RECORD in your global table.
Then, you will need to create a lookup field to lookup the attachment from the other table.
Now, you can attach that Excel file whenever a record triggers your email automation.
Alternatively, to do this more simply — without adding extra clutter & extra automations to your base — you can always use Make's automations which can pull attachments from any cloud storage space (such as Google Drive).
There is a small learning curve with Make, which is why I created this basic navigation video to help. I also provide the links to a few other Make training resources there as well.
p.s. If you have a budget for your project and you’d like to hire an expert Airtable consultant to help you with any of this, please feel free to contact me through my website: Airtable consulting — ScottWorld
