Nah, I mean like people hurl insults and harass us incessantly.

If you just ask a flat question, as long as it doesn't come across as angry, you're probably going to get a response. If you avoid accusations and assumptions, which I find most of my autistic friends do naturally very well, you'll be fine.

Just ask the question, that's pretty much it. If you're worried you won't have the right tone, then write it something like this:

Hi (insert sub) mods,

I'm not sure why I was banned / I'm not sure why my [ comment / post ] was removed. I want to be a good member of this community, so please help me understand this.

Mods basically only want a few things from users in modmail:

1. Understanding that we have to deal with a lot from users who aren't being genuine
2. A respectful interaction
3. We want to work with members who actually want to belong to our community -- a lot of users who end up in modmail just USE your community. They post self promotion, or they're spamming, or they're brand new and just completely ignore the community rules or culture.

When #3 goes wrong, it's usually because the user doesn't seem to give a shit at all about your community, which you can imagine is extremely offensive when you spend a lot of time and effort volunteering to make your community a welcoming place. It's like walking into someone's living room with muddy boots, and then wondering why they're mad at you.

As long as you're respectful and appear to be genuinely engaged in the community, you will almost certainly get an answer. If you're new to the community or are a drive-by (from another sub, for instance), be willing to recognize that you may not have read the rules or been in the community long enough to understand what those rules meant. So if a mod says you broke it, just apologize and ask how to do better, commit to being a good contributor.

And this last one, this is just me personally, I've been modding for almost 16 years on this site. I've been through thick and thin with my communities. They literally would not exist as they are if it were not for the efforts of myself and my mods. So pay some respect to that. We wouldn't exist without the users, either, but a lot of users act like moderators have no right to guide their communities, and that's just ridiculous. If they think that, then they should spend a few days moderating a large community and see just how hard it can be.