Actually the only mechanism for a server to find out which software was used to send a message is looking at the 'X-Mailer' or the 'User-Agent' headers. Those headers are optional so most of the time they do not even exist.
There is nothing else MaxBulk Mailer does a regular mail client application doesn't. The SMTP protocol (RFC 821) is the same for all e-mail programs, there is no command that says "Hello, I am a bulk mailer, can I continue?" so a host can't grant or deny access. There is no special protocol either for bulk emailing, only one protocol to send messages over the internet. A server however is free to display a welcome message to you with an advice on unsolicited e-mail delivery similar to:
220-server.mydomain.com ESMTP Fri, 27 Jan 2006 08:22:48 -0800
220-We do not authorize the use of this system to transport unsolicited,
220 and/or bulk e-mail.
220-server.mydomain.com ESMTP Fri, 27 Jan 2006 11:26:54 -0500
220-NO UCE. This server does not authorize the use of its computers or network
220 equipment to accept, transmit, or distribute unsolicited e-mail.
Note that those 'Welcome' messages have nothing to do with the software being used, they are just default messages the server displays to absolutely all the people connecting to it. The difference with MaxBulk Mailer and other programs is that you will see them as part of the connection log. Usually the applications with a user interface never display those messages nor the SMTP commands sent to the server in order to not confuse the user. (Note that you can see those messages through a Telnet session as well: telnet earthlink.net 25)
MaxBulk Mailer includes a header editor you can access through the preferences. This editor lets you add, remove or edit custom headers. You could add a custom 'X-Mailer' header to simulate your messages are being sent with a given program: