diff --git a/bin/mailsync b/bin/mailsync
index 9750ca3..ea645c3 100755
--- a/bin/mailsync
+++ b/bin/mailsync
@@ -3,6 +3,7 @@
 
 # Checks for internet connection and set notification script.
 ping -q -c 1 1.1.1.1 > /dev/null || exit
+pgrep -x mbsync >/dev/null && echo "mbsync already running." && exit
 
 export DISPLAY=:0.0