In the Tools>Mass Email form, when you send a Mass Email with the Bcc option box ticked, the To: address in the Mass Email will automatically be filled with the address shown in the Global Config>Server>Mail Settings>Mail from: field.
At the same time, the From: address will also be automatically filled with the address shown in the Global Config>Server>Mail Settings>From Name: field.
The reason for mentioning this is that if you enter your own personal name in the Mail from: field - and which would seem to be the logical choice - the recipient will see your name in the To: field of the email they receive, and may think the email has been sent to the wrong address. If you experiment with the settings, you'll see what we mean.
To avoid potential confusion on the part of anyone receiving a Mass Email, we suggest that the Mail from: field is entered as email@example.com, or similar. This should mean that recipients of a Mass Email will know exactly why they've received the email and that it's not potentially spam, or has been sent to the wrong address.
We also suggest that you set up 'email forwarding' or a POP account for the selected address e.g. firstname.lastname@example.org, so that recipients can reply to your email.
We suggest you keep the Bcc option box ticked so that you're not revealing and distributing everyones' email address in possible contravention of the Data Protection Act.
Bcc stands for 'blind carbon copy' by the way. It means that the email address declared in the Bcc field will get a copy, but no one else should be aware they have - unlike the way the 'cc' field works, where you're clearly advertising to the addressee who else will get a copy.