Author mail not working on submission and gives an error message in ojs 3.2.1

Hello,
I’m currently working on ojs 3.2.1 everything works fine and good but there a constant issue of submission mail and error message for all the authors I have applied all possible setings and changed the php.inc file also all the other mails are working fine but the submission mail isn’t it would be really appreciated if someone give me a possible solution for this
Thanks.
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