Sorry for the confusion. We don't need to create an alert to add additional messages to the email that gets sent out upon sharing in webconsole. The existing email message template can be modified and additional messages can be added to it. Please follow the below procedure. Hope it helps.
1. From the Commcell Console, right-click the CommServer -> Properties and open the Additional Settings tab.
2. Create below additional setting. You can type the additional setting name and click the lookup button and the default HTML template of the email gets loaded automatically in "value" field. You can then copy the existing template from the value field and use an HTML editor to modify the template to add any additional messages to it. Please do not remove tokens like $MESSAGE_TITLE and $MESSAGE_CONTENT. Once the modified HTML is ready, copy it to the value field and then save it. The next email message automatically uses the new template.
For details on this additional setting see below doc link.
||Modified HTML template