The description of the find familiar spell states:
Finally, when you cast a spell with a range of touch, your familiar can deliver the spell as if it had cast the spell. Your familiar must be within 100 feet of you, and it must use its reaction to deliver the spell when you cast it. If the spell requires an attack roll, you use your attack modifier for the roll.
This means that the spell is counted as originating from the familiar; however, the caster has to cast the spell for it to work.
Most spells, aside from sacred flame, can't target creatures in total cover because there is no direct line of sight to them.
As part of casting the spell, does the caster have to have direct line of sight to the target, or can they use their familiar's line of sight for this purpose? Is this what is meant by the text, "your familiar can deliver the spell as if it had cast the spell"?