As you surmise this is part and parcel of the use of BCC. (long winded history/explanation follows. I hope it is helpful.) BCC is very extensively used in the EU where individual privacy is [https://ovic.vic.gov.au/privacy/resources-for-organisations/eu-general-data-protection-regulation/ guaranteed by law] I have linked to an Australian government web site as it places an international perspective on what is local law in the EU. BCC is also a good choice when sending emails a group of associates or friends as it does not disclose any email addresses other than the one in the TO: field. To hark back to the ancient (in my memory but considered ancient history by many) paper correspondence with actual carbon paper and typewriters you would address a letter and in a business context optionally include a CC: or BCC: recipient. Those letters stood for carbon copy (CC) and blind carbon copy (BCC) and the typist would remove the cover page to the original recipient before adding the BCC entries, thus making the inclusion of the BCC recipient totally blind to the original recipient. In other circumstances the original and all copies but the one for the Blind recipient copy would be removed before adding that addressing. When email came along, obviously what were considered standard communication protocols like original, carbon copy and blind carbon copy were implemented to mimic the paper world that the brave new world of the paperless office was going to replace. We have not gone paperless, but the mimicry is still there. When an address is included in the BCC list the mail is directed to that address, but there is nothing in the actual email to indicate it as a recipient address. It is truly blind. Google have taken this one step further and actively remove the recipients in the BCC list from the senders sent mail, so you have no record of even sending the mail to that address. At a fairly low level To: is actually not used in submitting an email to the SMTP server for delivery. The command used is RCPT TO and this is not carried over into the actual email that is sent, it is just essentially the verbal command to the SMTP server to deliver this message to this person (email address). The CC list and the TO: as well as the reply-to: data will be sent with the email, but it is not used to actually send the email for delivery. So as suggested earlier it could be to do with the use of BCC, but it is not necessarily how the email was sent as in truth BCC only exists in the email you write, not in the copy that is transmitted to the server. What can be said is your address was used in the RCPT TO part of the transaction with the server when sending the email. This is why you can get emails which do not include what you see as any sort of reference to yourself or your email address. You were mentioned in the equivalent to the paper envelope, but it is lost on delivery.