An Ipswich small business owner is fearing she will miss out on trade as Royal Mail is set to ditch Saturday deliveries for second class letters.
Louise Richardson, founder of Two For Joy Illustration, said she is "basically totally reliant" on second class post.
Plans were put forward by the regulator Ofcom for Royal Mail to ditch Saturday deliveries, something that could save up to £425million.
The regulator said that after a consultation, it had provisionally concluded that reducing the second class letter service to alternate weekdays, while keeping first class deliveries six days a week, would continue to meet postal users’ needs.
But Ms Richardson is fearing the changes will mean customers opt against buying from her company.
She said: "I'm basically totally reliant on it [second class post] - 95% of my customers will choose second class which is the standard delivery that I offer.
"I think since Covid people are more used to waiting a little longer and for a small business like mine, it really impacts what we do.
"This will affect not just me, but also my direct customers too as the nature of greeting cards of course is they're often going back into the postal system.
"More cards means more joy. I think this will force people to buy first class stamps or not send them at all."
Ms Richardson, who started her card and gift business seven years ago, is one of nearly 6,000 to sign a national petition from the UK's Greeting Card Association to force greater parliamentary scrutiny of changes to the postal service.
She added: "It's time for MPs to get involved and stop this spiral of decline which could ultimately result in Royal Mail calling time on an affordable second class stamp and increase costs for businesses and consumers alike.
"If they don't, we'll be left with a premium, uncapped, unregulated first class stamp beyond financial reach."
Announcing the Royal Mail changes, Natalie Black, Ofcom’s group director for networks and communications, said: “The world has changed – we’re sending a third of the letters we were 20 years ago.
“We need to reform the postal service to protect its future and ensure it delivers for the whole of the UK."