Any notification, demand, waiver or other communications in accordance with this Agreement shall be given to each other in writing and in English language, and shall be proper when delivered in person, when sent by telex, telecopy, or email.
However, they shall be regarded as given 10 business days after mailed with postal charge prepaid, with registered mail, and with a returen receipt requested, to the above-mentioned addesses or other addresses notifed of by either party to the other party pursuant to this Article.

из 1-го предложения только выражение......shall be proper when delivered in person....

...считаются должным образом представлеными/врученными в случае, если доставлены с нарочным//курьером ...