I fully sympathize with the postal worker whose spectacles fog up whilst wearing a mask. As I have have spent almost a lifetime wearing a mask in the operating room I had the same problem when spectacles became necessary.
I thought it would be useful to share my solution. That is, to pass the top tape below the ears. Most surgical masks had tapes which I then tied on top of my head. The bottom tape was then tied behind the neck. If loops are used they can be simply twisted so that the upper corner goes below the ears and the lower corner above the ears. If there is a stiffener in the upper fold of the material this should be firmly squeezed on to the nose. Once these measures are taken the exhaled breath is deflected downwards away from the spectacles.
I hope these simple measures help with this problem. I fear that public health guidelines will call for mask wearing in enclosed places for a while yet. Masks should also only be handled by their tapes, and frequent hand washing is important. These measures are for the good of all and not just the wearer, hence should be complied with in spite of problems.
Dr J.A.Spencer F.R.C.S.