-G

Indicates that the message being submitted from the command line is for relaying, not for initial submission. The message is rejected if the addresses are not fully qualified. No canonicalization is done. As noted in the RELEASE NOTES that are part of the sendmail distribution available from ftp://ftp.sendmail.org, improperly formed messages might be rejected in future releases.

-L tag

Sets the identifier used for syslog messages to the supplied tag.

-U

As noted in the RELEASE NOTES that are part of the sendmail distribution available from ftp://ftp.sendmail.org, this option is deprecated. Mail user agents should begin using the -G argument to indicate that this is a relay submission (the inverse of the -U argument).