I am applying for MS Computer Science, Fall 2018 at UC Irvine. Being an international applicant I ha

I am applying for MS Computer Science, Fall 2018 at UC Irvine. Being an international applicant I have to send the transcripts to the Computer Science Department as a part of the application process. But, I have some doubt regarding the same. They have mentioned on their site that -

Transcripts: Submit one official transcript for every post secondary program attended. Official transcripts must be in sealed envelopes as issued by the school(s) you have attended. Request current transcripts from every post-secondary school that you have attended, including community colleges, summer sessions, and extension programs. If you have attended UCI, you must request an official transcript; we cannot obtain them on your behalf. All transcripts must be sent directly from the Registrar’s Office at your previous institutions to the academic program to which you applied (NOT to UCI’s Graduate Division).

I have my transcript in sealed envelope of my undergraduate institution. Could I just post the sealed envelope to the corresponding department or it should be from the Registrar Office only ?

Thanks.