I give a brief overview on recent results in string field theory (SFT) concerning infrared divergent string amplitudes. SFT is constructed in such a way that it reproduces string amplitudes when these are finite. When these are divergent on the other hand, the amplitudes computed from SFT are finite and unambiguous. These amplitudes capture fundamental quantities like vacuum energy shifts and allow to make firm statements about background independence in string theory.
I take the opportunity to point to historical papers from Alessandro and collaborators which pioneered several topics I discuss.