Mail.app Email Account Settings

@arlomiller Per your request on the other topic I thought I'd share this script. I hope it's not too late. I would definitely test this and tweak it to your exact needs. And be aware that it will flush existing mail settings for the mail app. If you have any questions about it make sure to mention me in your comment so I'll get a notification..

#!/bin/sh

liu=$(who | grep console | cut -f1 -d" ")  #gives the logged in user
plb="/usr/libexec/PlistBuddy" #sets the path to PlistBuddy
filepath="/Users/$liu/Library/Mail/V2/Maildata/Accounts.plist"    #Sets the path for the Accounts.plist file
mailserver="mail.example.com" #Sets the mail server as a variable, make sure to change this to your mail server
mailaddress="$liu@example.com"    #Sets the email address, make sure to change your mail domain after the @
realname=$(dscl . -read /Users/$liu RealName | tail -1 | cut -f2 -f3 -d" ")   #Gives the "real name" of the logged in user
desc="Example" # this is the name given to the account that shows up in the Mail client
myuid1=$(uuidgen)   #creates a unique ID for outgoing(it's an apple default)
myuid2=$(uuidgen)   #creates a unique ID for incoming

#first we're going to quit mail and flush any existing settings
# !NOTE! - THIS WILL REMOVE ANY CURRENT MAIL SETTINGS!!!
killall Mail
rm -r /Users/$liu/Library/Mail

#the following lines creates the Mail structure because we're assuming this is a brand new user
mkdir /Users/$liu/Library/Mail
mkdir /Users/$liu/Library/Mail/V2
mkdir /Users/$liu/Library/Mail/V2/Maildata


#the following lines create the Accounts.plist that actually sets up the users mail.  These are all defaults that I saw created when I made an account with all my default settings
$plb -c 'Add AccountsVersion integer 3' $filepath
$plb -c 'Add DeliveryAccounts array' $filepath
$plb -c 'Add DeliveryAccounts: dict' $filepath
$plb -c "Add DeliveryAccounts:0:AccountName string $desc" $filepath
$plb -c 'Add DeliveryAccounts:0:AccountType string "SMTPAccount"' $filepath
$plb -c 'Add DeliveryAccounts:0:AuthenticationScheme string ""' $filepath
$plb -c 'Add DeliveryAccounts:0:ConfigureDynamically bool true' $filepath
$plb -c "Add DeliveryAccounts:0:Hostname string $mailserver" $filepath
$plb -c 'Add DeliveryAccounts:0:IsSyncable bool true' $filepath
$plb -c 'Add DeliveryAccounts:0:MaxMessageBytes integer 52428800' $filepath
$plb -c 'Add DeliveryAccounts:0:PortNumber string "25"' $filepath
$plb -c 'Add DeliveryAccounts:0:SSLEnabled string "YES"' $filepath
$plb -c 'Add DeliveryAccounts:0:SecurityLayerType integer 2' $filepath
$plb -c 'Add DeliveryAccounts:0:ShouldUseAuthentication string "YES"' $filepath
$plb -c 'Add DeliveryAccounts:0:UseDefaultPorts string "YES"' $filepath
$plb -c "Add DeliveryAccounts:0:Username string $liu" $filepath
$plb -c "Add DeliveryAccounts:0:uniqueId string $myuid1" $filepath
$plb -c 'Add MailAccounts array' $filepath
$plb -c 'Add MailAccounts: dict' $filepath
$plb -c 'Add MailAccounts:0:AccountPath string "~/Library/Mail/V2/Mailboxes"' $filepath
$plb -c 'Add MailAccounts:0:AccountType string "LocalAccount"' $filepath
$plb -c 'Add MailAccounts:0:ArchiveMailboxName string "Archive"' $filepath
$plb -c 'Add MailAccounts:0:ConfigureDynamically bool false' $filepath
$plb -c 'Add MailAccounts:0:DraftsMailboxName string "Drafts"' $filepath
$plb -c 'Add MailAccounts:0:IsSyncable bool true' $filepath
$plb -c 'Add MailAccounts:0:NotesMailboxName string "Notes"' $filepath
$plb -c 'Add MailAccounts:0:SentMessagesMailboxName string "Sent Messages"' $filepath
$plb -c 'Add MailAccounts:0:TrashMailboxName string "Deleted Messages"' $filepath
$plb -c 'Add MailAccounts:0:uniqueId string "LocalAccountId"' $filepath
$plb -c 'Add MailAccounts: dict' $filepath
$plb -c "Add MailAccounts:1:AccountName string $desc" $filepath
$plb -c "Add MailAccounts:1:AccountPath string ~/Library/Mail/V2/IMAP-$liu@$mailserver" $filepath
$plb -c 'Add MailAccounts:1:AccountType string "IMAPAccount"' $filepath
$plb -c 'Add MailAccounts:1:ArchiveMailboxName string "Archive"' $filepath
$plb -c 'Add MailAccounts:1:ConfigureDynamically bool false' $filepath
$plb -c 'Add MailAccounts:1:DraftsMailboxName string "Drafts"' $filepath
$plb -c 'Add MailAccounts:1:EmailAddresses array' $filepath
$plb -c "Add MailAccounts:1:EmailAddresses:0 string $mailaddress" $filepath
$plb -c "Add MailAccounts:1:FullUserName string $realname" $filepath
$plb -c "Add MailAccounts:1:Hostname string $mailserver" $filepath
$plb -c 'Add MailAccounts:1:IsSyncable bool true' $filepath
$plb -c 'Add MailAccounts:1:NotesMailboxName string "Notes"' $filepath
$plb -c 'Add MailAccounts:1:PortNumber string "143"' $filepath
$plb -c "Add MailAccounts:1:SMTPIdentifier string $mailserver:$liu" $filepath
$plb -c 'Add MailAccounts:1:SSLEnabled string "YES"' $filepath
$plb -c 'Add MailAccounts:1:SecurityLayerType integer 2' $filepath
$plb -c 'Add MailAccounts:1:SentMessagesMailboxName string "Sent Messages"' $filepath
$plb -c 'Add MailAccounts:1:StoreDraftsOnServer string "YES"' $filepath
$plb -c 'Add MailAccounts:1:StoreSentMessagesOnServer string "YES"' $filepath
$plb -c 'Add MailAccounts:1:ToDosMailboxName string "Apple Mail To Do"' $filepath
$plb -c 'Add MailAccounts:1:TrashMailboxName string "Deleted Messages"' $filepath
$plb -c "Add MailAccounts:1:Username string $liu" $filepath
$plb -c "Add MailAccounts:1:uniqueId string $myuid2" $filepath
$plb -c 'Add OutboxMailboxPath string "~/Library/Mail/V2/Mailboxes/Outbox.mbox"' $filepath

chown $liu $filepath    #gives user permission to their Accounts plist
chown -R $liu /Users/$liu/Library/Mail  #gives the user permission to their Mail folder structure

this method didn't work for me. I am using MacOSX El Capitan, could it be because of it that i need to change somethings in the script or i have to do some additional steps?