Github user kevdoran commented on a diff in the pull request:
https://github.com/apache/nifi/pull/2111#discussion_r136448958
--- Diff:
nifi-nar-bundles/nifi-email-bundle/nifi-email-processors/src/main/java/org/apache/nifi/processors/email/ExtractEmailAttachments.java
---
@@ -131,11 +132,15 @@ public void process(final InputStream rawIn) throws
IOException {
MimeMessageParser parser = new
MimeMessageParser(originalMessage).parse();
// RFC-2822 determines that a message must have a
"From:" header
// if a message lacks the field, it is flagged as
invalid
- Address[] from = originalMessage.getFrom();
+ if
(InternetAddress.parseHeader(originalMessage.getHeader("From", ","), false) ==
null) {
+ if
(InternetAddress.parseHeader(originalMessage.getHeader("Sender", ","), false)
== null) {
--- End diff --
Do you think falling back to "Sender" if "From" is not present for RFC
validation is desired behavior? According to RFC-2882, and the RFCs that update
it ([RFC-5322](https://tools.ietf.org/html/rfc5322),
[RFC-6854](https://tools.ietf.org/html/rfc6854)), the "Sender" field should
only be present if "From" is also present.
That said, @btwood, have you encountered email servers that use "Sender"
without "From"? If so, it might be worth considering adjusting the
implementation here to reflect what is likely to be encountered in the wild vs.
strict RFC specification.
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