Royal Mail officials have apologised to customers in East Yorkshire whose postal deliveries have been disrupted by the severe weather.
The firm said that although postal workers had delivered to the majority of addresses, some areas had suffered in recent days.
Royal Mail director Alison Wright said a range of measures were in place.
The Communication Workers' Union said it had an agreed set of guidelines with Royal Mail for severe weather working.
'Simply not possible'
In a statement, Ms Wright, the Operations Director for the North East, Yorkshire and North Lincolnshire, said in some place the weather conditions had deteriorated.
She said: "We apologise to those customers who have experienced delays to their deliveries as a result of the severe weather.
"I'd like to stress that we are continuing to deliver to the majority of addresses across East Yorkshire.
"Unfortunately, in some cases it is simply not currently possible to do so because of the weather, which has worsened in some areas in recent days.
"A range of measures have been put in place to ensure deliveries reach people as quickly as possible."
The Communication Workers' Union said the safety of staff was paramount.
In a statement, the union said: "For example, 'spikys' and 'snow-chain' anti- slip footwear devices - which have been successfully trialled in Scotland over the past year - will be issued to all Royal Mail delivery and collection staff in order to give a safer footing.
"However our members have been asked to remain aware of safety hazards and if they feel their delivery walk has become too dangerous or inaccessible due to poor weather, managers will support their decision not to carry on and will encourage them to return to the office."