、？
Glaring resentfully at the bright-red letter — is this the infamous 'red paper' I've heard about?
Literal
Deep-red [attributive-な] letter [object-を] resentfully-[adverbial-げに] stare-[ren'yōkei-め], this [subject-が] infamous red-paper [quotative-って] guy is-[question-のか]?
Narrative prose shifting mid-sentence from third-person description to the character's internal thought (a free-indirect discourse technique). 忌々しげ uses the appearance suffix ~げ on 忌々しい ('vexing') to form 'looking resentful.' 真っ赤 'deep red' (with intensifier 真っ~). 赤紙 'red paper' is historically the WWII draft notice — conscription notices were printed on red paper, so the word became synonymous with the dreaded draft. ってヤツ 'the thing called,' katakana ヤツ for colloquial emphasis. 悪名高い 'infamous, notorious.'