"Technical issues" have seen a post office shut for weeks.
The Post Office, on Station Road, in Portslade, has been closed since February 19.
A notice currently displayed in the stores window states: "Due to technical issues we are unable to offer post office services today. The shop is open as normal.
"We apologise for any inconvenience caused."
A letter, seen by The Argus, from Post Office manager who also advised customers of the unexpected closure.
He said: "We are working to restore Post Office services at Portslade, and I apologise for any inconvenience the closure may cause locally.
"In the interim, we hope that out customers will continue to use Post Office services."
However, no re-opening date seems to be in sight at this time.
A spokeswoman for Post Office said: “Portslade Post Office has been temporarily closed since February 19 due to unforeseen circumstances.
"We apologise for any inconvenience caused by this unplanned closure. We are working to restore Post Office services at Portslade.
"In the interim alternative branches include Mill Lane, Parade and Blatchingdon Road.”
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The full addresses of alternative branches are:
Mill Lane Post Office, 95 Mill Lane, Portslade, Brighton, BN41 2DF – 1.03 miles away
Parade Post Office, Co-op, 5 The Parade, Hangleton Road, BN3 7LU – 1.06 miles away
Blatchington Road Post Office, 92 Blatchington Road, Hove, BN3 3YF - 1.3 miles away
