Despite postal delays of up to two hours in some rural areas, CAO college offers were delivered without problems on the second day of the pay dispute between the Irish Postmasters' Union (IPU) and An Post.
Similar delays were set to continue over the rest of the week, according to the general secretary of the IPU, Mr John Kane.
"The strike is at a very early stage," he said. "It is not possible yet to see what cumulative effect the action is having.
"We will see the results more clearly by the end of the week."
The 600 members of the IPU contracted to run rural post offices are refusing to accept deliveries from central locations until 8 a.m.
They would normally begin work two hours earlier.
Postmasters are also refusing to supervise and assist mail-sorting.
Mr Kane said he expected that there would be an accumulation of undelivered post at centres across the State, causing delays of up to 1½ days.
This scenario was rejected by a spokesman for An Post, who said that while there were delays it was an "absolute nonsense" to suggest that there would be a significant backlog by the end of the week.
"We are watching this situation very carefully; there are no build-ups, the mail is being cleared and delivered.
"We are emphatic about that," he said.
The delays are thought to have been minimised by the fact that there is a lighter flow of mail at this time of the year.
Some 47,000 students received CAO forms yesterday morning after An Post made special arrangements for their delivery.
Postmasters have been paid €2 an hour for supervising and assisting with mail-sorting.
Their union is looking for a €40 per hour increase for sorting duties and for post offices opening before 8 a.m.
An Post has said the contracted postmasters have already received significant pay increases over the past five years.
No further talks are planned between the two parties.
Commenting on the dispute, Mr Mark Fielding, chief executive of ISME (Irish Small and Medium Enterprises), said it was particularly problematic for small companies who rely on the postal service for cheques in payment for goods and services delivered.
Mr Peter Kavanagh, a manager at Seamless Aluminium Ltd in Co Donegal, said he received only one letter out of a normal daily postbag of 40 on Monday.
"Most of those missing would have been cheques.
"Small firms depend on being able to control their cash-flow. You cannot run a business like this," he said.