Three men face being sent to prison for blowing up the cash machine at Saltdean Post Office just over a year ago.
They stole £33,000 in the raid and a further £20,000 in a similar raid on a post office in Shoreham three days later.
They also escaped with £54,000 from the post office in Hurstpierpoint later in March.
Two of the three men were convicted by a jury at Croydon Crown Court today (Thursday 8 March) after a trial.
The other defendant pleaded guilty before his partners in crime went on trial.
They targeted the cash machine at the post office in Longridge Avenue at about 2.40am on Tuesday 28 February last year.
It was one of seven cash machines that they attacked using explosives in just under two months. They are believed to have stolen about £150,000 in that time.
The first robbery took place outside Bexhill Station and the next three raids targeted cash machines at garages.
Ermias Fekade, 37, and Joel Spears, 31, were convicted of causing explosions and conspiracy to steal, with Stephen Fahri having already admitted his role in the thefts.
They came unstuck last April when they left an explosive device by a cash machine at a post office in Southborough, near Tunbridge Wells, Kent.
The Crown Prosecution Service said: “The thieves fled the scene (and) were arrested near by following a car crash.”
Senior crown prosecutor Katie Samways said: “This was a series of dangerous offences putting members of the public who lived in close proximity to the explosions in grave danger.
“The CPS was able to build a compelling case against these defendants using a variety of evidence gathered by the Metropolitan Police.
“This evidence included forensics, mobile phone evidence and complex investigation techniques which ultimately lead to the defendants’ arrests.
“The common attributes of the offences included the similar early morning timing of the offences, the use of expensive sports cars as mission vehicles and all but one of the ATMs (automated teller machines) being in post offices or garages.
“In total £150,000 worth of cash was stolen and similar amount of damage caused over the course of seven offences. Thankfully their eighth and final offence failed.”