Reply To: BCC and Gmail
I thought it was the MTA’s job to convert a message containing a Bcc line into new messages with the Bcc line removed, but apparently that’s debatable.
That page mentions that some MTAs will leave the Bcc line in only the sender’s copy, so maybe for other recipients it is being removed?
Here’s a Thunderbird support article. It says that Bcc recipients are required to be hidden from To and Cc recipients, but not necessarily other Bcc recipients.
Since the MUA is a factor, maybe there’s a difference when sending from Thunderbird versus sending from the Gmail web interface?