create example.com & mail.example.com at once

A mail DNS record is already created (for use for SMTP and POP3/IMAP, generally, though it's not required, and some folks prefer to use a single domain for all POP3S/IMAPS connections so they can use a single certificate).

So, if you want mail to simply alias to the www.example.com/example.com site, you could just add this line to the Apache website section of the Server Template:

ServerAlias mail.${DOM}

For existing servers, you'd need to add the alias in the Services:Configure Website:Networking and Addresses page in the field labeled "Alternate virtual server names".

You can't use the usual "Create Alias" form, because there already exists a mail.example.com name in the DNS zone (and other places). Other auto-generated addresses are ftp, m, and www.

A mail DNS record is already created (for use for SMTP and POP3/IMAP, generally, though it's not required, and some folks prefer to use a single domain for all POP3S/IMAPS connections so they can use a single certificate).

So, if you want mail to simply alias to the www.example.com/example.com site, you could just add this line to the Apache website section of the Server Template:

ServerAlias mail.${DOM}

For existing servers, you'd need to add the alias in the Services:Configure Website:Networking and Addresses page in the field labeled "Alternate virtual server names".

You can't use the usual "Create Alias" form, because there already exists a mail.example.com name in the DNS zone (and other places). Other auto-generated addresses are ftp, m, and www.

why not create webmail.example.com and install squirrelmail in there for users to log in?

A mail DNS record is already created (for use for SMTP and POP3/IMAP, generally, though it's not required, and some folks prefer to use a single domain for all POP3S/IMAPS connections so they can use a single certificate).

So, if you want mail to simply alias to the www.example.com/example.com site, you could just add this line to the Apache website section of the Server Template:

ServerAlias mail.${DOM}

For existing servers, you'd need to add the alias in the Services:Configure Website:Networking and Addresses page in the field labeled "Alternate virtual server names".

You can't use the usual "Create Alias" form, because there already exists a mail.example.com name in the DNS zone (and other places). Other auto-generated addresses are ftp, m, and www.

it seems to me that upgrading a script to a newer version i.e updating should not be influenced by the number of accounts it holds.
Then again I am not familiar with squirrelmail.