Issue with "append" in

Hi all,

I have a customizer field where people fill in a mail address. The generated code however adds a space and that causes issues with other parts of my theme:

<?php if( get_theme_mod( 'myclient' ) ) : ?>
    <a class="mr-2" href="mailto: <?php echo get_theme_mod( 'myclient', 'mailto:' ); ?>"><i class="fa fa-envelope" title="Facebook"> </i></a>
<?php endif; ?>

As you can see, after the href="mailto: comes a space. This is not in my original html code. Also I cannot edit that in Pinegrow.

Can anyone advice on how I can solve this?

kind regards.