There is a problem in sending block e-mails in the Bcc field.
Firstly there has to be something in the "To" field and that can be your own address.
Secondly, spam filters can sometimes regard anything that is not "To" the recipient (per se) as spam.
And a lot of e-mails all looking the same look like spam.
I get round this when checking my website entries by running a macro in Outlook (Office). It effectively sends one e-mail per person, which generates many e-mails to send.
But macros in Outlook are a step more obscure than (say) Word or Excel, and macros in the latter 2 can be daunting for the casual user.

I came across a ridiculous situation with Helloprint.com - the website didn't spell all requirements in detail for artwork, so they auto e-mailed back. I waited and missed deadlines, all the time getting spam e-mails selling their other services. When I got in touch they suggested looking in the spam folder (of my provider's webmail!!!!).
How clever is that? Important messages diverted, junk gets through! They didn't understand my point either. I didn't use them again.