A condolence card should contain a brief message of sympathy for its recipient, such as "we are sorry for your loss." Brief messages allow the writer to show concern even if he did not know the deceased very well, and those who wish to express more may purchase a commercial sympathy card to reflect this.
Most short condolence messages express that the recipient is not alone in the grief she bears. Such messages may include the writer simply telling the recipient that he, too, misses the deceased or that the writer is sharing in the sadness currently felt by the recipient.
For writers who were friends or coworkers with the deceased, it is acceptable if the message reflects this relationship. An example would be the writer telling the recipient that he enjoyed working with the deceased for the last few years or that he fondly remembers the time he shared with the deceased during college.
One of the most common condolence message themes is that the writer's thoughts are with the recipient. This includes him telling the recipient that the latter is held in his thoughts or the thoughts of his entire family. A variation of this message is the writer expressing a specific desire, such as his hope that the recipient remembers the happy moments with the deceased even while mourning.