The Ministry of Defence is asking the public to donate to military charities instead of sending surprise Christmas parcels to troops they do not know.
In recent years, many well-intentioned people have sent gifts to combat zones in Iraq or Afghanistan, asking that they are passed to service personnel.
But the MoD says this deluge has stopped personal letters and gifts from friends and family arriving in time.
Last Christmas, the public sent 21,000 sacks of mail to troops in Afghanistan.
The Mod said this volume of post caused problems with its "logistics chain".
BBC defence correspondent Caroline Wyatt said that while the letters and gifts sent in by the public were appreciated within the Armed Forces, the MoD is keen to prevent the problems caused by the volume of post at Christmas last year.
Vice Admiral Peter Wilkinson, Deputy Chief of Defence Staff said the military's "logistics chain", which was there for "operational effectiveness", was hampered by the amount of Christmas post with which it had to cope.
"We need it to move supplies, ammunition, food, out to the troops, and there has to be a question of priorities," he said.
The post sent out to troops is usually transported by helicopter, but these remain in short supply.
This Christmas, the British Forces Post Office will limit its free postal service to friends and family, only accepting mail addressed to a named serviceman or woman, to ensure their cards and gifts get through on time. The MoD says that those who wish to show their support this Christmas should donate money to Armed Forces charities instead.
My own personal view on this is that, the MoD should make provision for the kind and generous gifts that the public send to our troops in places like Afghanistan and Iraq. While I can understand the senior officer’s problems in logistics they know that every year this happens and should plan for it. This is great for morale and makes the Armed Forces believe that they are appreciated. I have been in is situation and believe me, there is no better feeling than receive a gift pack from a member of the public back home. They are a few soldiers and airman who have no family contact and this service is a godsend for them. So come on, ignore the MoD carry on sending your packages they are appreciated and loved, these senior officer’s haven’t got a clue.