3 cupsWhite flour - plain, all-purpose, self-raising, speltWHITE FLOUR - GRAMS TO CUPSGramsCups300g1¾ cups + 2 tbsp400g2½ cups500g3 cups + 2 tbsp•Sep 20, 2018
"All" is not a proper noun. Only proper nouns (personal names) are capitalized. Note, when ending a letter, the proper grammar is to use "Best regards," or "Thank you,".
In the salutation, or greeting, capitalize the first word, proper nouns, and other nouns. When using phrases to replace a proper noun (like ''To Whom It May Concern''), capitalization is also expected.