sendmail limit & config

We have a process that sends an email to people via sendmail. Recently, that list of people exceeded some limit (about a thousand bytes in the list of email recipients) and sendmail is inserting a space in the middle of one of the recipient's email, thus corrupting that email address.
It appears, there should be a config file in /etc/mail where I can manipulate this limit, but my system does not even have a /etc/mail directory, so there is no config file.
Please advise.
Note that I need to use sendmail because that is how all of our emails are sent.
Running Redhat 7.6.