"In order to ensure tickets are received in time, we recommend you use a trackable postage method to return the tickets to us. Any tickets not returned in time will not be eligible for a refund," the email reads.
"Please note we are unable to refund you for the return postage."
However, those who bought an e-ticket or have not received their paper tickets yet will be refunded automatically within the next seven days, according to the email.
Viagogo also said customers cannot scan the tickets and email them to the business.
A Viagogo spokesperson told the Herald in a statement it guarantees a full refund, including shipping costs, if an event is cancelled.
"In some cases, for instance in transactions where paper tickets have already been shipped to buyers, Viagogo may ask customers to return their tickets in order to be refunded.
"Unfortunately scanning and emailing is not an option as in most cases the seller will need to return the physical ticket to their point of purchase for them to qualify for a refund.
"If sellers don't require the tickets back then Viagogo can refund the buyers who have received paper tickets without requiring the tickets to be returned.
"If an event is postponed, Viagogo follows the policy set out by the event organiser. Tickets are usually valid for the new date."
Metallica announced their highly anticipated New Zealand tour has been cancelled on Saturday after frontman James Hetfield checked into a recovery programme to deal with ongoing addiction issues.
"We are truly sorry to inform our fans and friends that we must postpone our upcoming tour of Australia and New Zealand," the rest of the band said in a statement.
"As most of you probably know, our brother James has been struggling with addiction on and off for many years. He has now, unfortunately, had to re-enter a treatment program to work on his recovery again."
Viagogo has caused controversy in New Zealand before after customers who brought tickets through the company's website weren't able to access the event they paid for.
The company has faced hundreds of complaints from Kiwis over its selling practices and the Commerce Commission alleges it has made false representations to its customers.
In July, Google suspended the ticket reseller as an advertiser after finding it breached the search engine's advertising policies.
Previously, Google searches for sporting and musical events would turn up Viagogo as the first result.
In response, Viagogo said: "We were extremely surprised to learn of Google's concerns today. We are confident that there has been no breach of Google's policies and look forward to working with them to resolve this as quickly as possible."
In April, The Commerce Commission appealed the High Court's decision not to issue an injunction against the website.
The commission had gone to court seeking to prevent Viagogo from making claims about ticket scarcity, pricing and a guarantee of validity. The commission alleged those claims were misleading.
A judgment for this appeal is to be delivered through the Appeals Registry at 3pm today.
At the February hearing, Viagogo said it had made changes to its website and sales process that addressed the commission's concerns - which its lawyer argued were in any case below the threshold of a Fair Trading Act breach.
But in March, there was further controversy as about 200 concertgoers were refused entry to a Six60 concert at Forsyth Barr Stadium when they tried to enter with "fraudulent tickets".
And as of June this year, the Commerce Commission updated that there was now an "unprecedented" 1034 complaints on its books relating to Viagogo.
