Defra reads a site postcode as a UK one only

The receiving site postcode has to be a UK postcode with its space in, such as CW12 1AB — an Irish one is fine for a carrier but not for a site.

What to do

1. Press Open site settings.
2. Add the space into the site's postcode.
3. Press Save changes, then go back to the record and press Retry.

Tipslip sends the record to Defra again once you retry.