How can I set up SmarterMail to allow username authentication from a mail client instead of having to use a full email address?
When you migrate a mail server from certain mail software platforms to SmarterMail, you may notice that the accounts are migrated over with only the username instead of the full email address. This happens because some mail server software allows the use of only the username to authenticate such as IpSwitch's Imail server. This can cause problems for end-users if they have their mail clients set up with just their username instead of their entire email address. By default, SmarterMail only allows full email address authentication. However, you can set up SmarterMail to allow username-only authentication. Below are the instructions on how to set it up. This is known to work with SmarterMail version 15x. It has not been tested with other versions of SmarterMail. Also, a special thank you to Scarab from the SmarterMail forums for providing us with this information.
1. Set each domain to a unique IP Address in your DNS server zones
2. Add your IP Addresses to the NIC on your Smartermail Server
3. Add your IP Addresses & Hostnames to IIS
4. Add your IP Addresses & Hostnames to Smartermail (SETTINGS > IP ADDRESSES and SETTINGS > HOSTNAMES
5. Set each domain in Smartermail to the appropriate IP Address under DOMAINS > EDIT > OUTGOING IP (probably an unnecessary step but helps in keeping your Domains segregated for reputation).
OPTIONAL: If you want webmail to use a secure session for each domain you would have to add a Security Certificate for each Hostname in IIS and an IIS Binding to the appropriate IP Address & Hostname. Letsencrypt certs work just fine for this purpose. You do not need to add these Certs to Smartermail as that only needs the Security Cert for the primary Hostname.
Basically if at login the Hostname they are attempting to login from has only one Domain Name in Smartermail bound to it then they do not have to authenticate with their full email address.