The cut is in the host they already use and the client has "a few thoughts." Your assistant drafted a recap of the creative journey. The journey is not the version. Picture locks on a version.
A live review is right when they have not seen it. Writing is right when they have, and you need a sentence you can hand to editorial.
Name the cut as if they have one tab open
Ask for a decision: lock picture on cut 4, or change only the notes you list, or hold for one more review. Give length, the date of this cut, and the two or three changes since the last one they signed. Name the response shape so "thoughts" is not a legal answer.
Give the honest deadline — colour, mix, delivery — not a nervous Friday. Say what you will do if you do not hear: hold the calendar, or lock the cut you named and treat later notes as a new job.
Do not attach the picture. RelayLink does not carry attachments. Point at the host you already use, and describe the cut in words so a person who cannot open video on this train can still know which file you mean.
Notes are a list, not a mood
If they already sent notes, restate the ones you will take, the ones you will not, and why, in a form they can contradict line by line. A paragraph that says you "addressed the pacing" is how a locked cut reopens at the screening.
Mark the premises. You assumed the logo at 0:04 is the one they still use. You assumed the interview bite stays. You assumed the music cue they liked is cleared. An assistant will write those as facts. Label them.
One decision per message. A second cut of a different film is a second briefing.
You approve it; they reply from email
You review the package. Use the project title they use. A nickname you keep in your contact list does not travel into the briefing.
They do not need an account. Most clients will answer from the mail and never sign in. If they already have an activated account, a new thread needs an accepted pair. If two stakeholders must sign, one briefing still goes to one mailbox. Say who else has to watch before you treat the reply as a lock.
After they lock
Write back "picture lock on cut 4" and the date, and ask them to correct that sentence. Then stop taking story notes on that cut. The next message is a different job — captions, a recut, a new deliverable — and it deserves its own ask.
The screening can still surprise you. The email should not be where you discover they thought this was a draft.