Contact alice@example.com or bob@example.org for details.
Send an email to alice@example.com (preferred) or to support@acme.co.uk.
This line has nothing interesting.
Multiple in one: a@b.com, c@d.io, eve.user+tag@sub.domain.example
Tricky stuff like @invalid or no-at.com should not match.
Repeat alice@example.com once more for the tally.