Abellio Greater Anglia say they hope the disruption caused by over running engineering works at Colchester should be resolved by lunchtime.
All lines are now open, however disruption is expected until around 12:00.
Ticket restrictions have been lifted, and today's tickets may be used on Tuesday. The company is still advising passengers to avoid travelling if possible or to revise travel plans.
To add to their problems the company website had crashed.