I'll keep this brief because I don't want to give too much information about myself or write a gigantic wall of text.

At my university, there is an organization that focuses on female electrical engineering students - let's call it Organization A. Organization A receives university funds for its events, and so it is not allowed to restrict membership based on gender and thus, I am a member.

I received an email from them earlier this month asking for all upperclassmen interested in being mentors for freshmen in EE. After filling out the application, it became clear to me that organization A is offering this mentoring program to both male and female students because they specifically asked if I wanted a mentee of my gender, to which I said I didn't care.

Earlier today, I received an email from Organization A explicitly telling me that I was not going to be selected for the program because I am male. They claimed that they wanted to start small and "grow" the program and thus, did not feel it necessary to "add males to the situation."

I emailed the other men copied on this email and encouraged them to report this to the university. Two of them wrote back to me and told me I was making something out of nothing and that I should calm down and not include them in any report.

I went ahead and reported the email to my university's diversity office with full copies of the initial recruitment email, the email excluding me for being male, and the contact information of all the men who hadn't asked to be excluded, but I'm not sure if I should do anything else. Has anyone else dealt with a similar situation? Would you recommend going to any other office to deal with this? Who could I escalate this to if the university takes my pretty damning evidence and tells me to take a hike?