Upvote:0
I don't know how that could happen
(couldn't make it to the visa center in time before my trip for example)
Then you have no passport, full stop. And entering Ireland/the UK without a passport is of course impossible if you require a visa in the first place.
If you use a keep your passport service (where you keep your passport while the application is in process and return it to get stamped), and don't return your passport for stamping, your visa application will be refused, even if it had been approved in the first place.
Will it help if I get by email and print the positive visa decision that Irish embassy sends?
This doesn't happen, visa decisions are never sent by email (this will likely only happen in Australia/NZ where all visas are fully electronic, and no stamps are applied) but are carried in sealed letters, along with the stamped (or not if refused) travel document to the visa center. Neither you nor the visa center know what the decision is before you get your passport and open it.