Hastings accountant Preston Epplett says he has been inundated with support from all over New Zealand after Hawke's Bay Today revealed his plight over delayed Xtra emails.
Two weeks ago some Xtra emails were blocked after two of three Xtra routers were blacklisted as spam agents.
Mr Epplett said "frustration followed by anger and costs incurred" meant he was seeking compensation.
Paula Rewi, of Accomplish Vocational Services, said her company had suffered delayed emails since March and had missed deadlines for a Government contract.
"Although I have provided feedback to our key client that delays have been subject to the email outage, and that Telecom technicians are working on resolving the issue, we are now in May and we are still experiencing email outages - which does not instil confidence in my client's ability to receive timely emails," she said.
"We are currently in the process of researching another provider to meet our IT needs.
"Again we are disappointed with the lack of timely action taken by Telecom and feedback on keeping us in the loop regarding resolution."
Telecom social media manager Richard Irvine apologised for the failures and said he had thought the problem had been solved last week but numerous reports to the contrary had proved otherwise.
"Our techs are looking into customers reporting ongoing problems.
"We take every customer having issues very seriously, and take on board your feedback on customer communication - we're reviewing our approach here."
Mr Irvine said the problematic servers were part of Yahoo's infrastructure in Australia.
Hawke's Bay music promoter Keith Gosney said he had experienced great problems with Yahoo's email service "a few years ago" when they kept blacklisting his bulk emails as spam.
He said customer service was "terrible".
"They would never tell you what to do," Mr Gosney said.
He had solved the problem by sending the emails in smaller batches, with differing subject lines.
Jim Peters, of Waipukurau, said he had logged 11 hours in January trying to resolve a Yahoo Xtra email issue - an issue that was widespread throughout New Zealand - where people were told their username and password were invalid.
"The only people I could talk to were in some country called the Philippines - there is nobody you can talk to in New Zealand," he said. "The service was appalling and there was me with no legs, in a wheelchair, deaf in one ear."
In 2007, Xtra customers were given one week's free internet as an apology for email problems and Telecom donated $1 million to charity.
Mr Irvine said thousands of customers would had experienced delays with the latest failure.
Customers were not told of the problem but the information had been posted on Telecom's website.
Mr Irvine said customers who would like to talk about the impact on their business were welcome to get in touch with Telecom to discuss the matter.