Mass communication refers to the process of transmitting information, messages, and ideas to a large audience simultaneously. It involves the use of various channels or mediums to reach a wide range of people. In the given options, the means of mass communication are as follows:

(1) Internet:
- The internet is a global network that allows for the exchange of information and communication across different platforms.
- It enables mass communication through various channels like email, social media, websites, online news portals, etc.
- People from different parts of the world can access and share information instantly, making it an effective means of mass communication.

(2) Postcard:
- While postcards can be used for communication between individuals, they are not typically considered a means of mass communication.
- Postcards are usually sent to specific recipients and are not intended to reach a large audience simultaneously.

(3) Television:
- Television is a widely used medium for mass communication.
- It allows for the broadcasting of audio and visual content to a large audience simultaneously.
- Television networks and channels provide news, entertainment, educational programs, and other content to viewers around the world.

(4) Telephone:
- The telephone is primarily used for one-to-one communication between individuals and is not typically considered a means of mass communication.
- However, it can be used for live interviews, phone-in shows, and other forms of interactive communication that can reach a larger audience.

(5) Radio:
- Radio is a popular medium for mass communication, particularly for audio content.
- It allows for the broadcasting of music, news, talk shows, and other programs to a wide audience.
- Radio signals can reach remote areas and provide information and entertainment to people who may not have access to other forms of media.

(6) Newspaper:
- Newspapers are a traditional means of mass communication and have been widely used for centuries.
- They provide written news, articles, opinions, and advertisements to a large readership.
- Newspapers can be distributed locally, regionally, or nationally, reaching a wide audience.

(7) Fax:
- While fax machines were once commonly used for transmitting documents, they are now less prevalent due to the rise of digital communication.
- Fax is not typically considered a means of mass communication, as it is generally used for one-to-one or small-scale communication.

In conclusion, the means of mass communication among the given options are the internet, television, radio, and newspapers. Therefore, the correct answer is option 'D' (1, 3, 5, 6 only).