Now online retailers facing threat from customs check
Levi's jeans, Apple technology and Sephora beauty products are all must have items for online Irish shoppers.
Jeans, mascara and iPads all topped the US shopping wish-list for Irish customers, while they are also turning to UK online outlets in search of fashion.
While 48pc of Irish people shop online at least once a month, Brexit poses a serious threat to the online retail market, according to An Post.
A spokesperson said 15pc of packages arriving here come from outside the EU and must go through customs.
But that would jump to 80pc in a post-Brexit world where there was no import deal from Britain.
A survey by the semi-State company showed how America is the international destination of choice for one in three shoppers buying beauty products and cosmetics.
One in five Irish consumers said they would most like to get their tech and electronic goods from Japan.
One in three Irish adults also admitted to asking friends and family bound for the US to bring specific goods home for them.
Brands referenced by survey respondents included Kylie Lip Kits, Christmas decorations, a Raiders American football helmet, Elvis memorabilia and Big Red chewing gum.
An Post's research found 46pc of consumers were most likely to shop on US websites when they cannot find their desired goods in Ireland or Europe.
While 42pc said that certain items are cheaper to purchase from US websites, one in four said unforeseen shipping costs can be a deterrent to online shopping.
Last year, average online shopping spend in Ireland was €553 per head.
An Post, launching its AddressPal USA service, which allows customers to order to a proxy US address and have the package delivered here, said some 125,000 people already use its similar service for the UK.
It said the market for delivering packages here was worth €600m a year, though Brexit could hit this.
"It would be dreadful for the UK retailers and it would be dreadful for customers," an An Post spokesperson said. "Even the logistics of it, there would need to be more Revenue staff, more warehouse staff.
"I wouldn't be in anyone's interest," she added.
The UK is by far the largest source of parcel traffic into Ireland followed by France, Germany, the Netherlands and the US, where the diaspora generates a huge level of traffic home.