We prove that an Anosov flow with C 1 stable bundle mixes exponentially whenever the stable and unstable bundles are not jointly integrable. This allows us to show that if a flow is sufficiently close to a volume-preserving Anosov flow and dim Es = 1, dim Eu ≥ 2 then the flow mixes exponentially whenever the stable and unstable bundles are not jointly integrable. This implies the existence of non-empty open sets of exponentially mixing Anosov flows. As part of the proof of this result we show that C 1+ uniformly-expanding suspension semiflows (in any dimension) mix exponentially when the return time in not cohomologous to a piecewise constant.Date: 20th November 2017. 2010 Mathematics Subject Classification. Primary: 37A25; Secondary: 37C30. With pleasure we thank Matias Delgadino, Stefano Luzzatto, Ian Melbourne, Masato Tsujii and Sina Türeli for stimulating discussions. We also thank Viviane Baladi, François Ledrappier and the anonymous referee for highlighting an issue in a previous version of this paper. We are grateful to the ESI (Vienna) for hospitality during the event "Mixing Flows and Averaging Methods" where this work was initiated. OB was partially supported by CNRS. KW was partially supported by DFG (CRC/TRR 191). 4 Stoyanov [34] obtained results similar to Dolgopyat [17] for Axiom A flows but, among other assumptions, required that local stable and unstable laminations are Lipschitz.