CODEWITHSUNDEEP
emailemail-headers
Torsten Homberger
Torsten Homberger

Reputation: 159

Unknown e-mail header `X-UI-CLIENT-META-MAIL-DROP`

I received an e-mail with this header:

X-UI-CLIENT-META-MAIL-DROP: W10=

I can't find any information about this header.

My suspicion is that this is a header set by the free email provider GMX, as I can only find this header in emails sent via GMX.

What adds this header, and what does the value "W10=" mean?

I searched the web but I was unable to find anything about this header.

Upvotes: 0

Views: 28

Answers (1)

phuzi
phuzi

Reputation: 13060

Any headers that begin X- are application specific headers and, unfortunately, there is no standard that the header name or value should follow. As such, without any documentation, W10= could mean anything.

For reference, this is documented in RFC 822 - STANDARD FOR THE FORMAT OF ARPA INTERNET TEXT MESSAGES specifically in Section 4.7.5 - USER-DEFINED-FIELD

Possible Base64 Encoding

On a hunch, the value W10= looks like it could encoded using Base64. Decoding it reveals the value [], but we cannot guarantee that it is actually a Base64 encoded string.

Upvotes: 0

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