Cross-border migration has increased rapidly in recent decades. In response, most democracies have extended voting rights to their citizens abroad. Nevertheless, expatriate voter turnout tends to be low. This article investigates a frequently proposed remedy - internet voting - based on a case study of extended internet voting trials in eight Swiss cantons. For causal identification, I exploit an unexpected federal intervention that led to a temporary suspension of internet voting in four of the eight cantons, during which expatriates could vote only by mail. Using difference-in-differences estimation, I find that the temporary suspension of internet voting decreased turnout among registered expatriate voters by 4.1 to 6.4 percentage points. Placebo tests suggest that pre- and post-suspension trends in expatriate voter turnout were close to identical in treated and control cases. Overall, the results of this study suggest that internet voting represents an effective method to increase electoral participation among citizens abroad. Still, expatriate voter turnout remained well-below domestic turnout even with internet voting available, suggesting that high voting costs are not the only reason why citizens abroad tend to vote at lower rates.