webmail access using webmail.mydomain.com

[Ron-e]

Getting "Internal Server Error"

Please do not double post.

Without any info about the error or what you have done we can not help you.
One option is to give us your etc/sentora/configs/apache/httpd-vhosts.conf file, most likely the error is there.

I followed above  ic.rezende's expatiation ,

</VirtualHost>
# Configuration for WebMail
<VirtualHost *:80>
ServerAlias webmail.*
DocumentRoot "/etc/sentora/panel/etc/apps/webmail/"
AddType application/x-httpd-php .php
<Directory "/etc/sentora/panel/etc/apps/webmail/">
Options +FollowSymLinks -Indexes
AllowOverride All
Require all granted
</Directory>

and in that file i can see my main domain entry
<virtualhost *:80>
ServerName mydomain.com
ServerAlias  www.mydomain.com
ServerAdmin admin@mydomain.com
DocumentRoot "/var/sentora/hostdata/zadmin/public_html/mydomain_com"
</virtualhost>

Then when ivisit : webmail.mydomain.com .I can see Internal Server error

Did yo end the webmail part with "</VirtualHost>", its not present in your text.