It comes after a "months-long" campaign to change the name.
An Post's passport application service has had its name changed due to complaints it was misleading.
Previously called Passport Express, it is now known as Post Passport.
Fine Gael TD Emer Higgins has welcomed the change, having called for the new name after highlighting the passport application service is not an express service.
This is as standard passport renewals take much longer to do via post than online.
“Applying for your passport by post is by far the slowest and most expensive means of application, with standard renewals taking up to eight weeks by post as opposed to 10-15 working days online," Higgins said in a statement.
“But up until now, I’ve found that a lot of people hear the name Passport Express and presume that it is the fastest method of application.
"I’ve delighted that An Post has now headed my calls and renamed the service to Post Passport."
Higgins said she had been engaging with An Post and Foreign Affairs Minister Simon Coveney on this matter as part of a "months-long" campaign.
https://twitter.com/EmerHigginsTD/status/1529180214512734209
"I think this new name will provide applicants with greater clarity and prevent people from mistakenly choosing the slower postal method if they can avoid it," she added.
“The main message for those applying for a passport is to apply online, apply early and ensure all your paperwork and signatures are in order and included with your application to avoid any delays.
“Especially with regard to first-time passports, which are now taking up to 30 days to process and require a lot more checks to be carried out than a standard adult renewal.
“I really welcome this name change and I think it will be hugely helpful along with continued measures to increase passport staff numbers and reduce waiting time."
In a statement to JOE, An Post said the name change came into force on Tuesday (24 May) following a period of engagement with the Department of Foreign Affairs and the Passport Office.
"Post Passport (formerly known as Passport Express) remains a trusted channel for passport applications and renewals, through all post offices," it said.
"We advise customers that the Passport Office is currently taking 6-8 weeks to process applications / renewals through the Post Passport channel."
