Yes, it is completely acceptable and normal to say "domo" in everyday Japanese conversation, provided it is used in the correct social context. As a casual, informal expression of gratitude or a brief greeting, native speakers use it constantly with friends, peers, service workers, and familiar acquaintances. It is especially useful for quick, low-stakes interactions where a full formal sentence would feel unnecessarily stiff or unnatural. However, while it is totally fine in casual environments, using "domo" in formal business meetings, when addressing senior executives, or when speaking to respected elders can come across as overly casual, lazy, or lacking in proper respect. Therefore, ensuring you match the word choice to the appropriate social hierarchy and relationship level is essential for maintaining polite communication in Japan.