Spell check on forwarded messages includes the original senders name in the check

When I forward an email and run a spell check occasionally the spell checker will trip up on the name of the original email (e.g. the Joe Smith wrote: part). This, for me, is happening on a surname like 'Gonen' or similar.

It would be great if PostBox could omit checking the spelling on this text which is automatically inserted (like how the forwarded message is skipped).