Photo size.

Since changing to Polaroid/Blipfoto I'm having to reduce my files to 75% of their original size. My files are large but Flickr accept them/reduce them themselves? ...and blip always accepted them pre Polaroid.
Its just a bit of a nuisance to keep having to go back and reduce them further...
Will this change? Is there a limit? It would be easier if I knew what it was. Thank you.