A 500-year-old oak tree that has its own postal address has become a letterbox for people seeking love partners after a couple whose relationship was forbidden tied the knot under it over 100 years ago.

The Bridegroom’s Oak which is located in the Dodauer Forest located near the city of Eutin in the German state of Schleswig-Holstein has been the world’s most romantic postbox for more than a century.

The old oak tree which stands still in the central part of the forest is at least 25 metres (82 ft) tall, whilst there is a knothole at a three-metre height (10 ft) which was secretly used as a mailbox in the past and is only reached through a ladder.

According to the tale, a forester’s daughter fell in love with a chocolate manufacturer from the city of Leipzig in 1890.

Since the father disapproved of their romance, the couple began to secretly write love letters to each other and hid them in the oak’s knothole.

However, the forester uncovered their secret after two years and gave his consent for their marriage, which occurred under the Bridegroom’s Oak on 2nd June 1892.

After the two married the oak gained international fame, whilst the knothole has served as a mailbox for lovers or for people seeking to find ‘the one’.

Postwoman Jule Engeldinger, 54, explained: “There are letters and postcards from all over Europe, the USA and Japan.”

The oak’s special mailbox has been officially used by the German post office (Deutsche Post DHL) since 1927 and has also had its own five-digit postcode since 1993.

According to the post office an average of 50 to 60 letters arrive at “Brautigamseiche, Dodauer Forst, 23701 Eutin” per month.

Engeldinger said: “If you are interested [in a person] you can take the letter with you, otherwise it will be put back.”

According to the German post office the Bridegroom’s Oak has connected over 500 couples including the one of a postman named Karl-Heinz Martens who found his life-long partner through a letter in the knothole.

He said: “I was the mailman for the Bridegroom’s Oak in Eutin for at least 30 years. There were several letters sent to the Oak that were addressed to me. I still have [some] of the letters.”

After Martens discovered a letter that caught his eye sent by Renate Heinz he decided to act on it and said: “Some time after we met. We are married to this day.”