Does this mail mean that I've been granted Visa?

EDIT: Another answer seems more accurate and up-to-date than mine.

It is hard to know until we find out a counter example (e.g. someone whose visa application was rejected), but I can share my experience of UKVI Istanbul.

I was granted three visas (two visitor visas, one work visa) between 2015 and 2018, they never disclosed the decision via e-mail. In 2015, phrasing of the e-mail was a little bit different as below.

[email protected]
Tue 16-Jun-15

Dear Customer

A decision has now been made on your application. Please allow 1-3 days for your documents to arrive at your visa application centre or to be couriered back to you (if you have purchased this option).

You can track your application on www.tpcontact.co.uk.

Regards

UKVI Istanbul Decision Making Centre

I don't think the word "successful" in your e-mail mean that the visa was granted. It should mean the process was completed. In any case, their phrasing is not clear.

EDIT: Some of the below answers maybe correct but my answer below is with the limited info provided in the original question. That said, I'd still use the guidelines detailed below:

There are a few things that make it suspicious for me:

1. The use of "Customer" instead of your name
2. "The outcome..." instead of clearly saying "Your visa has been approved" or "You have been granted a visa" or something clear like that
3. There is a chance that if you open the survey link, they will ask you for some sensitive information. Be careful. Usually service providers send a separate link, often, days after the appointment and the result to seek your feedback. I have so far not seen surveys being sent in the same email.

I'd also advise you to look at the email and see if it looks legit. You could call the consulate or the agency that helped you with your visa interview/appointment to see if the email sender is the right one.

Yes, it means that you got UK visa. And I can now definitely say that based on my experience.

In previous month we had 6 applications and all of them had the following email from the Istanbul Visa Decision Center:

Dear Customer

The outcome of your application has been successful and dispatched. Please allow 1-3 days for your documents to arrive at your visa application centre or to be couriered back to you (if you have purchased this option). You can track your application on TLS website.

At UK Visas and Immigration we continually strive to improve our customer service offer and would really appreciate your feedback on your experience via this short survey https://www.smartsurvey.co.uk/s/JYQ>SA/.Please be informed that your responses will remain anonymous.

Regards

UKVI Istanbul Decision Making Centre

We also had 2 applications which got visa refusal and email was a bit different:

Dear Customer

The outcome of your application has been dispatched. Please allow 1-3 days for your documents to arrive at your visa application centre or to be couriered back to you (if you have purchased this option). You can track your application on TLS website.

At UK Visas and Immigration we continually strive to improve our customer service offer and would really appreciate your feedback on your experience via this short survey https://www.smartsurvey.co.uk/s/JYQ>SA/ .Please be informed that your responses will remain anonymous.

Regards

UKVI Istanbul Decision Making Centre

So the difference is only in the word "successfull". If it there - you got your visa, if not - you get your passport with refusal letter. And it looks to be applicable to Istanbul center only.

When I did my web search - it appears that for Abu Dhabi center if the email says concluded than it means the visa was refused, if issued - than visa was granted.