You can set up your web widgets and campaign donation pages to automatically send an email when the donation is received - if you decide not automatically send the acknowledgment emails the emails will be queued up for you to send later - see Sending Acknowledgements in this article
To automatically send emails make sure that 'Send Acknowledgement Emails Immediately' is set to Yes on your web widget or campaign donation page - note that if you can change this setting for existing widgets and pages you do not have to regenerate the widget.
If there is a problem sending the email - e.g. your email server cannot be contacted - then
- the details of the problem will be stored in the comments of the transactions - see the example below
- the acknowledgment will be included in the list of outstanding acknowledgments - see Sending Acknowledgements in this article