The harmonic structure of minor keys is more complex than for major keys because, effectively, three different scales are being used simultaneously, so that the "natural" note choices expand to include both minor and major sevenths and sixths. In particular, the major seventh is often preferred to the (natural) minor seventh when it's a leading tone to the tonic, and this leading relationship notably occurs in the V-to-I progression--in your example, the E to Am progression--transforming the first chord from minor to major.

Note also that, in the natural minor, the diminished triad occurs on the II chord rather than the VII chord, and as the II chord is rather prominent in harmony (in the sequence of fifths, and thus in many progressions, it immediately precedes the V chord) some harmonic adjustment is usually made to avoid the diminished triad, for instance, by lowering the root (!) or raising the diminished fifth back to a perfect fifth (using the major sixth in the expanded scale).

More curious than the major E chord is the downward stepwise chord progression, since usually chord progressions are wont to resolve by fifths. So, pundits, why does that sound right? Is it just because all chord intervals move stepwise melodically, or is there a deeper harmonic explanation? After all, while it's common for IV chords to move to V, V chords move to IV much less often, despite that there is a leading-tone in V that could be said to resolve to the tonic in IV, crossing parts. That doesn't apply to the present example, of course (i-VII-VI-V-i...), but it does illustrate that stepwise chord progressions seem to follow a logic that conflicts in certain respects with normal expectations.