How do I send the gallery to the couple by email?

Send your “Gallery is ready” email from the gallery itself, now or on a day and time you pick.

Open the gallery's Share tab and find Send it by email.
Type the couple's addresses, separated by commas. The couple's emails from Access are already there.
Choose Now, or On a day and pick the day and the Time.
Leave Send me a copy too ticked to get the same email yourself, at your reply-to address.
Press Send (Send to 2 for two addresses). For a draft it's Publish and send, and for a planned email Plan it. Confirm in the box that opens.

Good to know

Each address gets an email of its own, so nobody sees the others. It comes from your sender name, and replies go to your reply-to email (both on Emails). Up to 10 addresses at a time.
A draft is published as the email goes, whether now or at the planned time.
Planned emails are listed under the button with Call it off until they go, then Sent, or Didn't go with the reason.
Times run from 07:00 to 21:30, every half hour, in your own time zone, up to a year ahead. The email goes within 10 minutes of that time.
The addresses you send to become the couple's emails, so their visits show as the couple in Activity. Your own address doesn't.
It greets them by the Couple's names in Settings › Access: “Dear Emma & Luca,”. With no names there, a gallery named just for them (“Emma & Luca”) gives its name; otherwise the greeting line is left out.

Why isn’t it working?

The button is greyed out: Add at least one address. An archived gallery can't be sent: restore it to drafts first.
It says Couldn't send to …: Check that address for typos and send to it again; the others have gone.
A planned email says Didn't go: The reason is under it, such as “Couldn't publish it: Add photos first.” Fix that, then plan it again.