In a given month I sent out over 100,000 emails to my website subscribers using a home-brewed email system. Meaning I don’t use the big players like ConstantContact.
When I send my emails out, and they are received at the receiving end, yahoo.com for example, could their virus check technically cause the email to show in my statistics as being “read”? The way I currently know if an email has been opened by the recipient is if the company logo loads inside the email.
Thanks for your help!
No it can not, the read message you recieve is sent by the email app, eg Outlook.
The feature to send recieved and read messages is an option you control in the email program, the virus check happens at the mail server.
Using that definition of read, then yes - virus scanners on the receiving end can download the image to see if it contains something malicious before showing it to the user.
That’s a different definition of “read” then the OP is using. You’re talking about read receipts, which is something different (and you probably don’t want in commercial emails, because they’re quite annoying).
Maybe I misunderstood the question or was I not clear. 
What I tried to say was: No, it can not show in your statistics as being “read” when it was scanned for virus.
Edit)
I clearly misunderstood the question, like I didn’t read how opened emails were detected. 
Lucky @rpkamp got what the issue was and answered adequately.
Are you able to determine when that happens? If the company logo loads soon after many of the messages are sent then I would assume they are being read by software, not a person.
Yes, I record a timestamp when the logo loads in the email the many recipient receive. And no, they all don’t get read at once. It takes days for the number of “views” to go up.
It seems unlikely to me that the virus scan would not happen very quickly after being received by an email server.
Given the nature of email I can very well imagine that things are scanned just in time, i.e., just before the e-mail is opened. This to prevent scanning millions of things that are in a mailbox that’s been abandoned and nobody reads anymore, thus wasting CPU power on absolutely nothing.
In other words, when it is opened and only when it is opened. So it would be the same thing, especially for your purposes, as if the message was opened without a scan, right? Remember that you said:
True, in that case it would be pretty much the same. Thing is, we don’t know and can’t know how this is actually being done for any given email provider, which is why I said “I can very well imagine” rather than “I know for a fact” - because I don’t.
