He retired from IBM's Thomas J. Watson Research Center in Hawthorne, New York in February 2009, and now works for FutureWei Technologies as a Director of Internet Standards.

He was part of the team that developed the SpamGuru anti-spam engine[2] at IBM Research.

[4] Leiba has been involved with the Internet Engineering Task Force (IETF) since the mid-1990s, working on e-mail-related standards, including IMAP, ACAP, updates to SMTP and the Internet message format, lemonade, the Sieve e-mail filtering language, internationalization in general and e-mail address internationalization in particular, and DKIM.

He has chaired a number of working groups, including DKIM,[5] OAUTH,[6] CBOR,[7] and DMARC,[8] and served on the Internet Architecture Board from 2007 to 2009.

He served on the Internet Engineering Steering Group as Applications Area Director from 2012 to 2016 and as Applications and Real-Time (ART) Area Director from 2019 to 2021, and is the IETF liaison to the Messaging, Malware and Mobile Anti-Abuse Working Group (M3AAWG).