Honkai: Star Rail is always filled with numerous random achievements with little description of how to get them truly. Spamming SPAM is a good example of this with its slightly misleading description of what you should do, despite being very simple to unlock at the end of the day.
How to Unlock the Spamming SPAM Achievement in Honkai: Star Rail
You unlock Spamming SPAM by sending a large message that hits the character limit to a friend while using the Trotter message chat box. The chat box’s name will be whichever you named your Trotter during the Aetherium Wars event, and you unlock it by completing it through the Conventional Memoir. You’ll get it immediately after beating the true final boss’ team in the Everwinter Hill area.
If you did this event back in 1.4, you should already have the chat box unlocked. Open the Messages tab and click on the small gear next to “Filter” to change your Chat Box. Once you have the Trotter box enabled, open your Friends list and choose your victim.
Just type something completely random to the person until you see the “Text entered is too long” message. When you do, hit “Send” and it’s done! It can be an actual message or just a bunch of “aaaaaa”s until it hits the limit.
You should see the achievement popping up on your screen. Remember to explain the situation to your friend. Or just leave that obscene amount of random text standing right there with no context. It might be better this way.
While the achievement’s description under the “Moment of Joy” category in the Achievements tab initially says “Feed Trotter in large quantities”, it later updates to “Use the X Chat Box to send a large amount of text content”. Another random achievement in the lot, but that’s just how it is.
This is far from being the last of those kinds of achievements you’ll meet in this game. Unfulfilled Wish is another good example, although that one is slightly harder to get.