As F.B.I. Pursued Snowden, an E-Mail Service Stood Firm

``Mr. Levison was willing to allow investigators with a court order to tap Mr. Snowden's e-mail account; he had complied with similar narrowly targeted requests involving other customers about two dozen times. But they wanted more, he said: the passwords, encryption keys and computer code that would essentially allow the government untrammeled access to the protected messages of all his customers. That, he said, was too much.''