Yes, can modify an email alert's "from address" to an email of your choice.
Please follow the below steps.
1. In the Webclient goto Admin tab > Report settings > Customize report.
2. Change the "From email" field to an email address with which the alert should be sent and click save.
Once done all your subsequent alert mails will be from the from address you configured. Hope this satisfies your requirement.
Product Manager, Site24x7