Registered e-mail address definition designates specified official or provided addresses for electronic delivery of tax communications. Section 144B defines Registered E-mail address as the address at which electronic communications may be delivered, specifying six alternative sources: the e-mail in the electronic filing account on the designated portal; the e-mail in the last income tax return; the e-mail in the Permanent Account Number database; for Aadhaar linked individuals, the e-mail in the UIDAI database; for companies, the e-mail on the Ministry of Corporate Affairs website; or any e-mail provided by the addressee to the income tax authority or its authorised person.