I'm not sure about the details of the contacts on WeChat and the details in the mailing process, but in general, mailing blood samples with ice packs has a certain impact.

During transportation, the temperature of the ice pack may affect the quality and stability of blood samples. If the temperature of the ice pack is too low, the cells in the blood sample may die or be damaged, thus affecting the test results. In addition, if the insulation effect of the ice pack is not good, or the transportation time is too long, it may also affect the quality of blood samples.

Therefore, if it is necessary to mail blood samples for testing, it is recommended to use professional transportation services to ensure the quality and stability of the samples. At the same time, it is recommended to consult a doctor or a professional for such operations.