The biggest bomb contained a copy of Space Jam: A New Legacy, featuring LeBron James.
The Spanish are easily intimidated by terrorism and that’s why this is happening. If they would fight back against the terrorists then it would stop happening.
In this case the terrorists are likely connected to Russia. The Basque Abertzale (a communist political and terror group) had ties to the USSR and KGB and is no doubt connected to these recent mail bombs.
Notably, one of the targets of the mail bombs is a Spanish firm that makes grenades for the Ukrainian Army. Thus it’s pretty easy to connect the dots.
Probably the Basque terrorists supporting their Russian comrades. (The Soviets backed the Basques just like they backed the Arab terrorists, IRA, radical US leftist terrorists, etc)
A sixth letter bomb: That would be an F Bomb.