Wrong glue for outside project

You’d think after 30years of woodworking you might stop making stupid errors but alas it appears not. On latest project making a post box I picked up the wrong glue pot by habit and didn’t realise until I’d finished the box that it was internal yellow glue. Only the rear French cleat was attached by external glue so I guess it’ll fall apart in situ!
So is there a clear finish I can use that will seal it in enough to prevent the glue failing? Thanks.

For those interested I’ve bought some boat clear varnish and going to give it a good few coats. Hopefully that’ll give it some longevity