Neil McKenzie, 41, of Saltcoats, and Trevor Muirhead, 43, of Kilwinning, both Ayrshire, made no plea or declaration when they appeared in private at Kilmarnock Sheriff Court before Sheriff Elizabeth McFarlane yesterday.
The men were arrested on Thursday following a major police investigation after suspect packages were sent to Lennon and one each to lawyer Paul McBride QC and former MSP Trish Godman.
A fifth suspect package, addressed to the offices of Cairde Na hÉireann (Friends of Ireland) in Glasgow, was also intercepted by officers last month.
All of the packages were found during March and April.
The Crown Office said that Muirhead and McKenzie each faced three charges of dispatching a package containing explosive substances under the Explosive Substances Act 1883.
They also each face two charges of dispatching a hoax bomb under the Criminal Law Act 1977.
Both were remanded in custody and the case was continued for further examination.
Yesterday’s arrests came as, in a separate incident, a man appeared in court charged with assault after an attack on Lennon at Tynecastle stadium during Celtic’s game against Hearts on Wednesday night.
Officers arrested a man after he clambered from the Hearts section of the main stand and made towards Lennon.
The manager was said to have been left “shaken” by the incident.
John Wilson, 26, from Edinburgh, has been charged with breach of the peace aggravated by religious prejudice and assault aggravated by religious prejudice.
He appeared at a private hearing at Edinburgh Sheriff Court yesterday afternoon.
No plea or declaration was made during the hearing and he was remanded in custody.