Following are the steps to reset the administrator password in smartermail.

1) Stop the SmarterMail Service
2) Open Windows Explorer (My Computer)
3) Go to C:\Program Files\SmarterTools\SmarterMail (or wherever one has installed SmarterMail)
4) Open the Service subdirectory
5) Make a backup copy of the file MailConfig.xml
6) Open MailConfig.xml in Notepad to edit the file.
7) Find the below mentioned code:

<!-- ** System Admin *************************** -->
<!-- ** To reset admin password, delete these items ** -->
<!-- ** and then restart the SmarterMail Service. ** -->
<!-- ***************************************** -->
<sysAdminUserName> ... </sysAdminUserName>
<sysAdminPassword> ... </sysAdminPassword>
<!-- ***************************************** -->

8) Delete those lines and save the file.
9) Start the SmarterMail Service.

You can now login into the smartermail by using following credentials.

Email: admin
Password: admin