Outlook may use a different default language than Word. Solution:
Do not settle for Brazilian Portuguese “general” dictionaries. Demand PT-PT precision. Your readers, whether in Lisbon, Porto, Coimbra, or Faro, will notice the difference. proofing tools office 2016 pt-pt
Highlight your text and go to Review > Language > Set Proofing Language to ensure the spellchecker is actively using Portuguese. Outlook may use a different default language than Word