1.12 is outdated, has reached end of life and is no longer supported.
You would want to upgrade to a more contemporary (read: is still supported) version.
My understanding is that Sendgrid is a email news letter service provider, not a email provider.
Does Sendgrid give you POP/IMAP and SMTP settings that you can use with a mail client?
- If yes, then you should be able to use it with osTicket.
- If no, then I doubt it will work for anything.