My dad somehow manages to get email addresses into group MMS chats, and each email response creates a new thread

/r/cospenis if this was reddit.

Disclosure: Am Vegan. Don't hate vegetarians.

I think it's because many Vegans perceive Vegetarians as going half the way and then stopping dead.

From a vegan perspective meat eaters are doing something morally wrong. But many have grown up that way and are conditioned into normalizing meat consumption. Many haven't questioned it ever, or reflexively defend it, because it is perceived as normal.

Vegetarians on the other hand seem to understand the problem of animals suffering. Many of them made an ethical decision not to eat meat... and then continue to contribute to animal suffering by consuming other animal products. Understanding that murder is bad and then deciding to commit it just a bit less directly, is a position many Vegans take as deeply harmful.

Personally i am grateful for every single animal saved. Reducing meat or going vegetarian are steps in a direcion i see as good and positive. In my ideal world we would all be Vegans, but i am grateful for every little step in that direction.

Not quite. Vegans don't eat any animal products of any kind. Vegetarians don't eat products that necessitate killing an animal to produce, but allow others. Note that these other products are usually from animals that will be killed for food, and that the animals that won't be murdered still also suffer.