To-Recipient Required in Email?

Question

I would like to know if a "To"-Recipient is required in an e-mail per definition or if all recipients could be Bcc or Cc.

RFC5322 states

The only required header fields are the origination date field and the originator address field(s). All other header fields are syntactically optional.

but what about the SMTP RCPT?

score 1 · Accepted Answer · answered Feb 20 '17 at 18:43

1

All recipients are described using the RCPT TO: SMTP verb; the fact that they are to be treated as "To", "Cc" or "Bcc" is only due to the message headers, which are part of the DATA portion of the SMTP conversation.

From the MTA's point of view, there is no difference at all: they are all recipients which must receive a copy of the message.

answered Feb 20 '17 at 18:43

Massimo

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Bottom line is, there is no requirement of a "To"-Recipient per RFC, correct? – LeRookie Feb 20 '17 at 18:46
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There's no requirement at all for *any* recipient in the message headers. – Massimo Feb 20 '17 at 19:33

To-Recipient Required in Email?

1 Answers1