email.utils.format_datetime()

email.utils.format_datetime(dt, usegmt=False)

Like formatdate, but the input is a datetime instance. If it is a naive datetime, it is assumed to be “UTC with no information about the source timezone”, and the conventional -0000 is used for the timezone. If it is an aware datetime, then the numeric timezone offset is used. If it is an aware timezone with offset zero, then usegmt may be set to True, in which case the string GMT is used instead of the numeric timezone offset. This provides a way to generate standards conformant HTTP date headers.