Space-agent and mailbox emails set From to {slug}-agent@rspace.online but
the envelope MAIL FROM was noreply@rmail.online. Rspamd DKIM-signs with
the envelope domain (rmail.online), which fails DMARC alignment against
the rspace.online From header — Gmail was quarantining invites.
Set envelope.from to match the From header so rspamd signs with
rspace.online's DKIM key and SPF/DKIM align. Verified via test send:
DKIM_SIGNED{rspace.online:s=dkim}, FROM_EQ_ENVFROM, no DMARC:Quarantine.
Covers: space invite emails (identity + existing-user paths), agent
notifications, rinbox MI agent blasts, mailbox approval sends.