RFC 822实际上给出了这种用法的示例。它要求（第4.4节）在使用Sender：标头时将其存在。
A.2.7. Agent for member of a committee
George's secretary sends out a message which was authored
jointly by all the members of a committee. Note that the name
of the committee cannot be specified, since <group> names are
not permitted in the From field.
From: Jones@Host,
Smith@Other-Host,
Doe@Somewhere-Else
Sender: Secy@SHost
废弃的RFC 2822继续明确允许这种特殊构造（第3.6.2节）。
from = "From:" mailbox-list CRLF
mailbox-list = (mailbox *("," mailbox)) / obs-mbox-list
在当前标准RFC 5322中，此内容未更改，并且仍然明确允许使用多个地址（第3.6.2节）。
The from field consists of the field name "From" and a comma-
separated list of one or more mailbox specifications. If the from
field contains more than one mailbox specification in the mailbox-
list, then the sender field, containing the field name "Sender" and a
single mailbox specification, MUST appear in the message.
它曾经有用吗？是的，对于古代示例中所示的情况，它仍然是。具有多位作者的邮件应在发件人：标题中列出所有作者，并将发件人：设置为在其电子邮件程序中实际按下“发送”的人员。
The originator fields indicate the mailbox(es) of the source of the
message. The "From:" field specifies the author(s) of the message,
that is, the mailbox(es) of the person(s) or system(s) responsible
for the writing of the message. The "Sender:" field specifies the
mailbox of the agent responsible for the actual transmission of the
message. For example, if a secretary were to send a message for
another person, the mailbox of the secretary would appear in the
"Sender:" field and the mailbox of the actual author would appear in
the "From:" field. If the originator of the message can be indicated
by a single mailbox and the author and transmitter are identical, the
"Sender:" field SHOULD NOT be used. Otherwise, both fields SHOULD
appear.
实际上，在公共Internet上，完成此操作的消息并不常见，尽管它们确实发生在企业和学术环境中，在这种情况下，一个人代表另一个人或一组人发送电子邮件的情况更为普遍。
我从来没有真正看到过垃圾邮件能够做到这一点（并通过其他所有控制手段）。我通常认为丢弃或提高此类邮件的垃圾邮件分数是不安全的。