Question about Thunderbird

[jd1008]

Running current TB thunderbird-31.1.1-1.fc20.x86_64

Received a message from a vendor I deal with, via paypal.
The message content was alright as I expected it to be.

However, TB displayed the From field as some other name,
other than <vendor's name> via paypal
which is usually how invoices come to me from paypal.
Except in this message (first time I see this), the from field
is from another entity.
I examined the full headers and I did not see the entity that
TB claims the message was from.

Does anyone have an idea how this can occur?