I have written a Python script that iterates through rows of an Excel file and, for each row:

Gets an e-mail address, name, and name of attachment file to use
Composes an e-mail
Sends out the e-mail

I'm not sure if it's accurate to call this mass-emailing or if it is a candidate for being black-listed because it is sending out individualized e-mails. With a message submission rate of 5/minute, I want to throttle it (or have the limit increased to 100).
So my question is: Is the sort of scenario, assuming the limit is increased to 100, prone to black-listing?
Its not easy to answer your question as it depends hardly on the remote email environment used here and what you understand with individualized emails (only a different "Hello Mr. ZZ" or "Dear Ms. YY" isn´t really an individualized email these days). To give you three possible examples:
Situation 1:
All users are on the same email environment (e.g. Exchange Online / Office 365). Then the remote mail server might see here +100 similar emails and might mark them as spam. If all +100 users are on +100 different email servers that might be different however the following might be possible:
Situation 2:
One user think that this email is spam and report that as spam. Depending on the AntiSpam engine used here a hash value from that email might be created and other email server using the same AntiSpam engine might therefore detect your email as spam as well.
Situation 3:
The users are on different email environments but in front of them is an AntiSpam cloud solution. This solution will then see +100 similar emails from one eMail environment and might therefore clarify that as SPAM.
Offtopic: You might consider using services like from MailChimp which use different email servers to spread out a similar email. This might help to prevent such issues as the mass emails aren´t send from only one server. On top of that you do not risk your own email server from being blacklisted which might have a very bad business impact on your company.
Python Email via MS Exchange: Message Submission Rate Limit