If an agile team has members like Developers, Testers, and Automation Testers from different geographical regions, how can the daily scrum meeting can happen? Obviously they have to work in different time zones. Can this be successfully managed? Do you think the daily scrum meeting can be replaced by sending status emails at the end of day, or by answering the three Scrum questions in an email?
In my experience nothing beats a meeting face to face - even if it's over a video conference link. In my current project, we have developers and Scrum team members all over the UK and we conference call in for a daily scrum. it works relatively well. I don't think emails status works as well because Scrum is supposed to be an arena for back and forth interaction. Save email status reports for project management updates. In projects where emails were the main focus for clearing issues, the delays became longer, people 'missed' emails, and eventually it slowed the project to a crawl.
Purpose of the Stand-Up
You're misunderstanding the purpose and intent of Scrum's daily stand-up. It's a task synchronization and coordination meeting between members of the development team, which requires n-way communications between team members in real time. You can't replace this with a daily email update and still expect to the team to remain agile.
Face-to-Face Isn't a Scrum Requirement
On the other hand, there's no actual framework requirement that everyone be in the same room, or even the same time zone. The underlying agile principle says:
The most efficient and effective method of conveying information to and within a development team is face-to-face conversation.
While in-person meetings provide the most communications bandwidth, it is still perfectly legitimate to substitute the most effective means of communication at the team's disposal. A video conference still provides plenty of opportunities for visual communication, and even a live teleconference allows for more socially-nuanced communication than online chats or emails.
While not ideal, you can make it work. The difficulty depends on how many time zones and how flexible the work day is for each of the locations. In the USA, most often it is done by holding the daily Scrum as early as possible for workers in the US and having overseas (Europe, western Asia) folks work a workday that is shifted slightly later, where they attend at the end of their workday. It is most challenging when the time difference is around 12 hours. For work in Australia and the US, the reverse is true.
Alternatively, I've also worked where there are a few representatives from the remote group involved in the Scrum, instead of everyone. This is less ideal but can still work pretty well, when supplemented by additional means of communication and good process and requirements gathering / communication (such as very good acceptance criteria definitions).
It's generally about the quality of the team members. Face-to-face is great, but you can make the remote work with smart people with good communication skills and positive attitudes.