Notify anyway, a Link’s ring and its invitation, a canvas or list notice and channel activity skip anybody who blocked or ignores the sender, wherever they made the block. Your own organization’s hold on your phone — signed out everywhere, or two-step required — now also holds notifications from channels and conversations another organization keeps.
A link preview waits at most a few seconds for the website, beside the rest of Kemble’s work rather than in front of it, so a slow website cannot hold up anybody’s notifications. A picture shown from a link is kept with its message, shown only to people who can read it, and deleted with its preview, its message or by retention.