Not sure how exactly people function in the ministry but if the Board made the error, shouldn't the minister or at least her PA checked it before it was sent to the teachers. It was going on her behalf after all..How can she sign without reading the contents? 

The notice was sent by the Secy. CBSE on behalf of Smriti Irani. The minister must not have insisted the Secy. to send it through her office. Because it was just a congratulatory letter addressed to the Teachers of all schools.

Spelling error can change the entire meaning so it is very important to check and re-check before sending a letter to anyone and this letter was being sent by a Ministry and that to, to the teachers. They should have been more careful because the buzz that got created for an error in spelling was not in a good taste.  

Spelling demons make or mar entire meaning of a sentence. Utmost care has to be exercised to avoid spelling mistakes. It is important in any sphere of life in communications.