Temporary Block CF7 Submit on Send

init.js

var wpcf7Submit = $('.wpcf7-submit');

document.addEventListener( 'wpcf7submit', function( event ) {
        wpcf7Submit.attr('disabled', 'disabled');
}, false);
document.addEventListener( 'wpcf7mailsent', function( event ) {
        wpcf7Submit.removeAttr('disabled');
}, false);
document.addEventListener( 'wpcf7mailfailed', function( event ) {
        wpcf7Submit.removeAttr('disabled');
}, false);
document.addEventListener( 'wpcf7spam', function( event ) {
        wpcf7Submit.removeAttr('disabled');
}, false);
document.addEventListener( 'wpcf7invalid', function( event ) {
        wpcf7Submit.removeAttr('disabled');
}, false);

Try shorter version:

var wpcf7Submit = $('.wpcf7-submit');

$('.wpcf7').on('wpcf7submit', function(){
    wpcf7Submit.attr('disabled', 'disabled');
});
$('.wpcf7').on('wpcf7mailsent wpcf7mailfailed wpcf7spam wpcf7invalid', function(){
    wpcf7Submit.removeAttr('disabled');
});