Many artists hard at work making multiple submissions weekly may send email to an art publishing company, for example, requesting their submission policy and guidelines. In the email subject line should the artist type Artist Inquiry or Artist Enquiry? Which is correct?
According to the Grammar Monster entry on inquiry vs enquiry, in both the USA and UK they are interchangeable words. However, in the UK the word inquiry denotes an investigation, while the word enquiry refers to a question asked.
In the USA, the word inquiry is more widely used and often the word enquiry is thought to be a misspelling of the word inquiry.
So, in practice, enquire and enquiry are more common in British English, and inquire and inquiry are more common in American English. This usage difference may be something to consider to help smooth over differences when doing business internationally. Little things can matter. Also, consider that Australia, India, South Africa, Hong Kong still commonly use British English, while American English may generally be preferred in other parts of the world, such as in Japan, S. Korea, Philippines, and Mexico. In Canada, it may be case by case–some use British English, some American English. When sending email to an arts professional in the USA perhaps it is best to use inquiry to avoid the appearance of a misspelled word. When sending an email to an arts professional in the UK you may want to use the preferred enquiry.