A man returned home late last night to find the front door of his property in Whitehawk on fire.
The owner extinguished the fire at the home on Coolham Drive and the emergency services attended the scene just after midnight.
It is believed a towel that had been put in the letter box to stop it rattling had been set alight which resulted in damage to the box and a doormat inside the property.
There was nobody in the property at the time of the incident.
If anyone witnessed the incident or saw anyone acting suspiciously in the area they can call Sussex Police on 0845 60 70 999 quoting serial 0001 of 22/09 or the independent charity Crimestoppers anonymously on 0800 555 111.