How can I save an attachment on account while sending an email in Salesforce?

Hi Laveena.

In Classic

1. Go to Setup.
2. Under Administer, click on Communication Templates | Classic Email Templates.
3. Click on the name of the email template that you would like to attach a file to.
4. Click the Attach File button.
5. Complete the three steps and click the Done button.

In Lightning

1. Go to any object that has Email publisher available.
2. Go to the Email tab.
3. Select the Email template that you wish to add an attachment to by clicking on the Insert, create or update Template button.
4. Select Insert Template.
5. Click the Attach file button and select the file you wish to attach to the template.
6. If you would like to save this template with the attachment for future use, click Insert, create or update Template and select Save Template.