Agreement of your institution
Academic institutions or their libraries usually negotiate detailed agreements with some publishers for access to their publications or for special conditions for open access publishing. Sometimes these agreements also include provisions on self-archiving that grant members of the institution special conditions for self-archiving, for example improved conditions with regard to the publication version that can be used or the embargo (see the explanations below). The agreements may even stipulate that the institution may carry out the self-archiving on behalf of the author. Simply ask your institution's library about such agreements.