Spanish Salutation: Buen día
Pronunciation: Booayn deeah
Translation: Good day
Function: Salutation
If you can´t remember the right time of day to use ‘buenos días’, ‘buenas tardes’ or ‘buenas noches’ you can always use the orthographically correct ‘Buen día’ at any time of the day (it can be used on writing too, as an introduction for all kinds of e-mail, formal or not)
If you don´t want to sound that formal, you can say the colloquial that locals use: ‘buenas’. They say it at any time of day, but mostly to their acquaintances
Example: Buen día tengan todos ustedes
Translation: Good day you all