Yeah, this happened often to me as well. Actually, it’s too limited; I think in the future they’ll charge for this service… it sad to say but we’re beta testers for now here.
To work around this, I’m creating a draft inside my Gmail account (already generated with Copilot or Perplexity) and I tell my R1 to take this draft to post. Anyway, I’m experiencing this very often, and I’ve understood that R1 is unable to copy and paste but it reads and later rewrites the message. So it would be great to get information from the Rabbit Inc. Team here about how many characters are permitted for our R1 because it’s really limited.
Probably they will definitely implement a paid model because all this token generation comes at a cost! …and not a small one. That’s why in another post I’m encouraging consideration of interaction with macro “repetitive operations” that our dear little rabbit could launch without wasting tokens. But I understand it’s difficult to both comprehend and implement this concept.
I suggest you vote for this feature 
…as suggested also from @iRockxul (Macro Creation) and someone else…