Code is from -
read/write smtp & pop config for outlook
Code:

$regKey='HKCU\Software\Microsoft\Office\Outlook\OMI Account Manager'

$Entry = ReadValue($regKey,'Default Mail Account') 



$rc=WriteValue($regKey+'\Accounts\'+$ENTRY,'SMTP Server','xxx.xxx.xxx.xxx','REG_SZ')

$rc=WriteValue($regKey+'Accounts\'+$ENTRY,'POP3 Server','xxx.xxx.xxx.xxx','REG_SZ')

$rc=WriteValue($regKey+'\Accounts\'+$ENTRY,'Leave Mail On Server',1,'REG_DWORD')

$rc=WriteValue($regKey+'\Accounts\'+$ENTRY,'Remove When Deleted',1,'REG_DWORD')

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