Rear door paint work bubbles

Ok quick question. The old 110 was repainted before I got her. Now most of it looks really good but the rear door is a suffering from bubbling and if you push them then they are filled with water. I have stripped the door and it looks like the frame had a rust problem and has been welded and repainted.
Another observation is that the bubbles are all along the bottom and everywhere behind the metal frame.
Now the plan is to por15 the frame work, get some dinitrol and fill the inside of the frame. That just leaves the question what to do with the outside paintwork and how to stop the water coming through?
Am I right in assuming the outset aluminium panel is porous and this is causing the water bubbles in the paint. If this is the case how do I fix it ?
Thanks in advance

The panels not porous but you might have water getting in through window seal, door handle cutout and any/all rivets.....also check where outer skin is folded over the edges

.....and the ali needs priming with an etch primer.......if it wasn't this may be the cause of the bubbling

Thanks beasty, the rest of the body is looking good so assume it was primed correctly. The window seal was fubar'd as they didn't put the bottom strip back so originally it leaked like niagra falls. I have put a new bottom on but now need to do it all again. Remove the glass, take out all the old tape and replace it and then screw the whole lot back down.
Hopefully that will stop the water getting in in the first place

What's happened is the rusty steel bits have reacted with the aluminium and left wee holes in it. When tye've sorted the steel work out, ye've not sorted the skin out. Ideally, ye should try and keep the two metals apart. Once yeve done that, ye need tae clean the skin around the rotten bits (don't use a wire wheel) then filler, etch prime and then paint

you will never stop it..2yrs at most before it comes back..new door skin required..

pop thec bubbles and paint the metal/corrosion/primer w.h.y. same colour as door..

Thanks all for advice. Looks like I will clean the inside and paint it, fill it with dinitrol and then get on with the outside paintwork in the spring.. Or get a new skin but that sound like a more tricky job to complete