MySQL's `utf8` character set is a little broken, and does not cover 4-byte UTF-8 characters. In most cases it will quietly truncate the string whenever it sees one, saving incomplete text data.  

In  5.5.3 they introduced `utf8mb4` to fix this inconsistency, and given that it's been 5 years, it's probably safe to encourage people to use it. If their MySQL installation is old, it should be easy for them to find the distinctive string and change it back to `utf8`.