I use the Airmail application for Macintosh as my email client. 

I've added some aliases (already configured in my Zoho control panel) but am unable to send email from those aliases via Airmail.

The SMTP settings in Airmail appear to be correct, and my main email address is able to send properly. It's only the aliases that don't work.

I've also verified that I can successfully send from the aliases when doing so through the Zoho webmail site.