Use single quotes in the password encryption example.
For password decryption, put the backquotes inside double quotes to
avoid special characters being re-interpreted.
set imap_user = ".....@gmail.com"
# To avoid storing your password in the .muttrc:
-# echo -n "mypassword" | gpg --encrypt -r 0x1234567890ABCDEF > ~/.mutt/account.gpg
-set imap_pass = `gpg --batch -q --decrypt ~/.mutt/account.gpg`
+# echo -n 'mypassword' | gpg --encrypt -r 0x1234567890ABCDEF > ~/.mutt/account.gpg
+set imap_pass = "`gpg --batch -q --decrypt ~/.mutt/account.gpg`"
set folder = imaps://imap.gmail.com/
set spoolfile = "+INBOX"