Isolating suspicious email links is described. An email security service receives an email that includes a link that refers to an external resource. A first suspicious link determination is performed to determine whether the link is suspicious. If the link is suspicious, the link is rewritten to refer to the email security and the email is delivered to the recipient. A request from a client device is received responsive to the link being opened. A second suspicious link determination is performed to determine whether the link is suspicious. If the link is suspicious, an interstitial page is transmitted to the client device that includes an option that, when selected, causes the first link to be opened in a remote browser isolation session.