Guests are expected to complete the title before writing their full name. For example, “Mr.”, “Mrs.”, “Ms.”, or “Miss” would follow naturally from that initial letter, depending on personal preference.
This tradition comes from older, more formal styles of correspondence. At a time when etiquette played a larger role in everyday communication, small details like this were considered standard and widely understood.
However, modern guests are not always familiar with these conventions. As a result, something meant to guide people can end up confusing them instead.
The good news is that there is flexibility. If someone prefers a different title or none at all, they can simply write their name in the way they feel most comfortable.
Ultimately, the purpose of the RSVP is not perfection but clarity. Responding on time and accurately matters far more than following a small traditional detail.
Once you understand it, that mysterious “M” is no longer intimidating. Instead, it becomes a simple reminder of how traditions evolve, and how even the smallest details can carry a bit of history with them.