sendmail error Enter mail, end with "." on a line by itself

We currently have a server built on Linux nginx with aws.

The following command has been completed.

(echo "Subject: test title"; echo ; echo "test desc") | sendmail -i -v xxx@gmail.com

I filled it out as above. The following results came out.

And I opened this file.(mail.log)

Mar 21 21:36:22 ip-123-123-123-122 sm-mta[28249]: 02LCaMUu028249: from=, size=419, clas nrcpts=1,s=0, msgid=<202003211236.02LCaMaL028248@ip-123-123-123-122.ap-northeast-2.compute.internal>, proto=ESMTP, daemon=MTA-v4, relay=localhost [127.0.0.1]

I just can't figure it out. Ask for help from the experts here. I'd appreciate it if you could help me. Thank you to everyone who reads this.