I have a custom domain on shared hosting, and apparently the hoster does not support DKIM. Is that really bad? I sent a mail from it to a gmail account, and i

I have a custom domain on shared hosting, and apparently the hoster does not support DKIM. Is that really bad? I sent a mail from it to a gmail account, and it was not flagged as spam Also, when I send a mail from my university address, it says, the DKIM user identifier does not match the from header