Postal voters at home and abroad fear they may have lost the chance to vote in the Scottish elections because of a delay in delivering ballot papers.
Production and distribution problems have been blamed, with forms failing to arrive at homes ahead of Thursday.
The problem has been highlighted in areas including Aberdeenshire and the Borders ahead of Thursday's elections.
The Electoral Commission's Andy O'Neill admitted that some people could miss out but the vast majority would not.
Councils said anyone worried about not receiving their papers should get in touch with them as soon as possible.
Comments sent to BBC Scotland's news website from voters living abroad include those from Raymond Mallon.
He said: "I am living in Belgium at the moment, and applied well before the deadline for my postal vote.
"The elections are on Thursday and I have not yet received my postal ballot. My vote is lost.
"Clearly there is not a good enough machinery in place to allow those overseas to vote by post. It is unacceptable that I should be effectively barred from voting by post simply because I live overseas."
Another voter, from Kingswells, said: "Somewhere along the line there is gross incompetence because it's totally unacceptable.
"Where does all the blame lie? This must be sorted out."
Mr O'Neill told BBC Scotland: "There have been some delays in terms of the distribution of postal votes. Our understanding is the vast majority have been distributed."
He said people in Scotland who had not yet received their papers could get a replacement or hand in their papers when they arrive rather than posting them back.
Of voters living abroad who had not received their ballot papers, he said: "In that instance you will not be able to vote. There does seem to be a small number of people who may not be able to vote."
Mr O'Neill said: "We have a duty to report and will look at it and learn from any of the lessons."
In Dumfries and Galloway a total of 1,600 voters were still waiting for postal papers at the end of last week. However, the council said these had been sent out on Friday and should have arrived at the relevant homes.
Meanwhile, a "small pocket" of voters was still without papers in the Scottish Borders, according to the local authority.
"We are doing everything we can to determine the extent of the problem and to help voters to get their papers in on time," said Returning Officer David Hume.
Ballot paper producer DRS admitted an increase in demand for postal ballots had put pressure on its print run.
It is understood the print run was completed last week and DRS said it was not responsible for distribution.
A Scottish Executive spokesman told BBC Scotland that there had not been any breach of contract in terms of getting postal ballots produced on time.
The Royal Mail said it would carry out special sweeps of delivery rooms throughout Scotland on the night of the elections to catch any late postal ballots which would then be handed over to election officials.
To learn more about how to vote on polling day, listen to Mr O'Neill's advice during Wednesday's special
with Maggie Shiels.
He will explain the different systems of voting and how long polling stations will be open.
The web broadcast will be available on BBC Scotland's elections site from 1300 BST.
We asked if you had experienced problems with the postal voting system. The following represents the balance of opinions received.
My wife and I requested a postal vote as soon as we knew we would be in Canada on holiday on the day of the election. We are now in Canada and our postal voting documentation has still not been received at my Dunfermline home. We did receive a letter on 26th April (dated 20th) to confirm we were eligible for a postal vote. As I was travelling on 27th I continually phoned the postal vote enquiry line to find out why we had not received our postal voting papers, only to experience a continually engaged tone.
I also contacted our MP's office, Willie Rennie to express my concerns, but sadly they could only advise me to contact the postal vote enquiry line. If this situation happened in a Third World country there would be questions asked about such things as attempted vote rigging, corruption, etc., but as we live in a "democracy" such things don't happen. A.H.L.McAllister
I work in Australia and a proxy votes on my behalf at elections. My voting papers have not arrived at my proxy's address (I spoke to them by telephone on Saturday). It is almost impossible to get in touch with Dumfries and Galloway Council to see what has happened. I know one vote will probably not make much difference but it is definitely the principle of the situation. I am registered to vote in one of the country's most marginal electorates (Galloway and Upper Nithsdale) and feel my vote does count. David Speirs
My wife applied for a postal ballot as she was going to be away on business on polling day. She flew off on Monday morning (30th) and the ballot papers duly arrived in the afternoon and hence she has lost her right to vote. This is an appalling state of affairs. What will happen if the vote is close in a constituency where a large number of postal votes are missing? Is there any way now that I could vote on her behalf? Gary Cameron
I'm registered to vote in the East Kilbride constituency. I live in the area but due to work commitments I am working in Belfast Monday to Friday. I signed up for the postal vote after being lead to believe I would receive the paper well in advance and allowing me to return the form before I went back to Belfast. My mother called me this morning to say that the form had just arrived. Not much good when I'm here. I've always voted and now I can't. They complain when there is a small turn out for the elections! No wonder when loads of voters aren't given the chance too! Murray
My daughter's postal voting papers have not been delivered. She is an RAF officer currently training on a base in England. My wife was assured last Wednesday by the election office at North Ayrshire Council that they were being sent out the next day (26 April) but had still not arrived by yesterday. My wife went to the election office in Irvine to pick up the papers yesterday and posted them off to my daughter by special delivery in the hope that they can be returned by Thursday. Our armed forces personnel are expected to put their lives on the line, yet are being denied their democratic rights. Iain Walker, Kilbirnie
I am registered to vote in south Ayrshire. I am currently living and working in Edinburgh and thought it would be better to do a postal vote as I could not get the time off of work to travel across the country. I received and posted my papers five days before the cut-off. The following evening I received a telephone call to say that I had miss the cut-off for the postal vote deadline. I then agreed to have proxy papers sent out to myself to nominate a family member to vote on my behalf. The letter arrived this morning with a post date mark of the 26.04.07 even though it was sent first class that has taken five days to arrive. This now means I am going to miss the cut-off date for proxy votes which is five days in advance to register.
The only possible way now for myself to vote is to travel from Edinburgh to Maybole (1.5hr journey) but this will not be possible because of my work commitments. I am extremely annoyed that I will not be able to vote because of a series of cock-ups and late post. Stuart Thomson
My father lives in Clynder, near Helensburgh, is 71 and has voted all his adult life. His postal vote - which he asked for because he has mobility problems - did not arrive until Saturday and at one point he was told he may have to go to Dumbarton to pick it up. He has since sent off his postal ballot and hopes it will arrive in time. It does strike me as leaving it a little late. I am sure there will be a significant number of people who lose their vote because of this. I don't know who is responsible but it should be thoroughly investigated to ensure it never happens again. We cannot spend a fortune trying to convince people to vote and then let them down.Gregor Addison
I am currently living in Ireland and missed the deadline for postal voting, however I was still able to register to vote by proxy - nominating a member of my family to vote in my place. I registered to vote this way over two weeks ago but have yet to hear anything back. Brian, Dublin
My parents requested a postal vote as soon as they were able to, knowing they would be on holiday on the day of the election. They are now in Canada and their vote has still not been received. When I phoned the postal vote enquiry line to find out why this had happened, I was told that as well as printing problems, the requests were held over so they could all be sent out together. The whole thing is a farce. J.Knox
My son is at university in Edinburgh and his postal vote was arranged well in advance. Now he has lost his vote. We need to establish who is responsible for this debacle. This denial of voters rights must surely be a criminal offence in a democratic country. Eric Hamilton
Just wanting to add my voice of concern over delayed ballot papers for the Scottish election. I live in France and have maintained my registration to vote since moving here. I voted in the last UK general election having received my ballot paper in time. I am still waiting for my ballot paper for voting May 3rd. This will of course be too late now. I will be contacting my MP as I find it unacceptable that so many overseas voters are being denied their vote by what seems incompetence. Dale Rowe, France
Here in the West Lothian/Livingston constituency I too am having problems with my postal ballot. The problems aren't simply related to those overseas, I'm currently working during the week in Bristol, so I applied for a postal ballot. I have my mail forwarded to my temporary address.
My wife called up yesterday from our home in West Lothian to complain that I hadn't received my ballot yet and was told that I could hand in my ballot at the polling station, despite being told twice that I was in Bristol. Sometimes the incompetence of local government workers just flabbergasts me. It's not as if the election was a big surprise snap election.
If it arrives today or perhaps tomorrow I might have to go to the expense of paying for a courier to get my ballot there on time. GMcD
I live in Liverpool and organised a postal vote well in advance of the elections. By Saturday the 28th it had still not arrived and I returned to Scotland for my holiday. I notified my local office and they said no problem they would send a new ballot to my home address within 24 hours.
I didn't receive my postal vote but instead another two for my parents, who have already sent their two back. I rang back and they blamed the company in charge but informed me I would again receive my ballot in 24 hours, wishful thinking perhaps...It's a joke and the buck seems to keep getting passed.Craig Barrie
My husband and I are in Washington DC as he is posted here. We were unaware we had been taken off the electoral roll until a few weeks ago. By the time we applied for a postal vote we had missed the first deadline for ballot papers to be posted.
Even if we had made that deadline it would still have not been enough time for us to return the ballot papers. People abroad who wish to vote are being disenfranchised by a system that does not allow enough time. I was very eager to vote in this election and now as a result of this I have lost that chance. Marie Therese Hayes, Washington DC
Hi, I'm a 20-year-old student who is registered to vote in the East Kilbride constituency. I have not however received my postal vote as of today, and have phoned up to enquire to be told I have to come to Hamilton to pick up a vote if I want to vote. I find this completely unacceptable since I'm at university in St Andrews and can't travel home in the next few days.
I did receive my postal vote at the Westminster elections two years ago. I am a little cynical since I did intend to vote SNP. Craig Marsh
I am a postal voter in Aberdeenshire and I received my papers through last week. This is in plenty time to allow proper review of the paper and return within the required time frame. If the papers can be issued to some people on time then why not all? I think that it is pretty poor of the voting system that they are blaming it on a print run and are not responsible for distribution when it is quite clear from my receiving papers that a print run has been carried out and they have been put into the distribution system.
Surely the postal system is not that poor and judging by the amount of unsolicited mail that I have received to my address with party propaganda they have no problem delivering this unwanted waste so why not able to deliver ballots? John, Aberdeenshire
My parents who live in Aboyne did not receive their postal ballots in time before going on holiday despite assurances from the local returning officer. Prisoners in Scottish jails will almost certainly get compensation for not being allowed to vote. Will similar compensation for not being able to exercise constitutional rights be afforded to the hundreds of people affected by these administrative shortcomings? Richard Salway
My son asked for a postal vote for his university residence in England, after being persuaded to do so by some government people in a shopping mall in Dundee. It didn't arrive. He's come home now, but finds he can't vote in person because he is registered for a postal vote. The best they can do is send another ballot paper to ... his address in England. What a shambles. The only consolation is that he was going to vote Labour! John Sutherland, St Andrews
I spoke to my elderly parents last night just before they went on holiday today. They applied for postal votes nearly 3 weeks ago and have received nothing. They complained to North Ayrshire Council who said there papers were "in the post" and took no responsibility. So that's two more SNP votes lost due to the incompetence of Labour local authorities. Paul, Glasgow
My son is living in Norway. He is only 19 - so his first chance to vote. He applied as soon as he could for a postal vote, but his postal vote has not even arrived yet - so absolutely no chance of his vote getting in on time and being counted. He commented that he had received a letter from the SNP at his address in Norway (he is not a member) and thought it pretty ironic that a political party had managed to get their material to him on time, but the authorities' incompetence had disenfranchised him. He's pretty cross about it.
People are worried about young people not taking an interest in voting - here was one young man who firmly believes in democracy and was really looking forward to his first vote. How many other young people on gap years have been affected? And how about the armed forces serving abroad, who are reported to be ready to 'give Labour a kicking'? Are they going to be unable to register their opinions, as well? It makes the cynical amongst us wonder if this is a form of vote rigging? Susan