Illegal string offset warning when trying to send an email from Admin

Emails are getting through, but this warning fills the page when sent.

Warning: Illegal string offset 'EMAIL_TO_NAME' in includes/functions/functions_email.php on line 83

Warning: Illegal string offset 'EMAIL_TO_ADDRESS' in includes/functions/functions_email.php on line 84

Warning: Illegal string offset 'EMAIL_SUBJECT' in includes/functions/functions_email.php on line 85

Warning: Illegal string offset 'EMAIL_FROM_NAME' in includes/functions/functions_email.php on line 86

Warning: Illegal string offset 'EMAIL_FROM_ADDRESS' in includes/functions/functions_email.php on line 87

Warning: Cannot modify header information - headers already sent by (output started at includes/functions/functions_email.php:83) in admin/includes/functions/general.php on line 21

What version of ZC?
What version of php is the server running?

PHP 5.44, ZC1.38 completely patched up past 1.39 to work with PHP 5.44.

The error above was actually from when I was resending archived emails.

If I send a normal message from the admin side to a user, this is the error messages

Warning: Illegal string offset 'file' in includes/functions/functions_email.php on line 255

Warning: Illegal string offset 'file' in includes/functions/functions_email.php on line 255

Warning: Illegal string offset 'file' in includes/functions/functions_email.php on line 255

Warning: Cannot modify header information - headers already sent by (output started at includes/functions/functions_email.php:255) in admin/includes/functions/general.php on line 26

Fixed the 'file' error messages, inserted new code from Zencart 1.6 files into my includes/functions/functions_email.php and all working perfectly with no errors.

Stilll have the Warning: Illegal string offset 'EMAIL_TO_NAME' in includes/functions/functions_email.php on line 83 from Email Archive Manager, though this is a third party extension.

Did you manage to get this resolved?

I am getting the error > Illegal string offset 'EMAIL_TO_NAME' in when sending mail using the Autoresponder plugin.