What are your mail DNS records?
Any domain name using our nameservers will automatically have 'smtp', 'pop3' and 'imap'.your-domain.tld hostnames created, and MX records automatically pointed. If you're managing DNS externally, or wish to use the stack hostnames directly, the following can be used to access our mail services:
IMAP: imap.stackmail.com
POP: pop3.stackmail.com
SMTP: smtp.stackmail.com
MX: mx.stackmail.com
The above hostnames will work for all mailboxes on our platform.
If you wish to configure Outlook Autodiscover support, please create a CNAME for "autodiscover.yourdomain.com" to point to "autodiscover.stackmail.com".