Methods, systems, and computer program products for reducing unsolicited electronic messages by using immutable email identities in place of traditional email addresses. Over any of various protocols, an address generation server receives an electronic message requesting a disposable address for an intended recipient having an immutable email identity. The request also includes a return address for the sender, which discourages unsolicited messages because most senders of unsolicited messages prefer to remain anonymous. After receiving the request, the address generation server creates the disposable electronic message address, which may be limited in use. A challenge must be completed before the address may be discovered or used. This challenge further discourages unsolicited electronic messages because it imposes a burden that many senders of unsolicited messages are unwilling to bear.