Urgent: June 2nd deadline. Spam or True? Email says I must change my snet.net email to classic.

Please could you respond to me as soon as possible.  I don't want to lose my email account.

I received the following e-mail today, copied and pasted below. 

From:  mySnet.net Support <[email scrubbed]>

Subject:  Account Update Warning!

Here was your logo in .png, recreated as best I could:   Currently, | Yahoo!

                                                                                      from AT&T

We've upgraded your mailbox for a smoother, more efficient email access security experience.

Dear Valued Customer,

The old version of our mailbox will be shut down on the 2nd June 2023, You are required to update your Snet mail to the new classic version of our mailbox. Failure to do this, you will lose your Snet email access. 

Click Here to  Sign in to Upgrade Now

Thank you for choosing us.

Sincerely,

Snet Mail Management

Here's what I've done.  First I tried to verify as follows:

1.  I went to my yahoo page rather than clicking on the email.  Found instructions at update classic version yahoo mail - Video Search Results, but the instruction to click on switch to classic mail did not appear under my settings.

2.  But now dubiously confident that the email could be trusted, I clicked on Click Here to  Sign in to Upgrade Now which unfortunately took me to Error .  Oops!!  Suspicious again!

3.  Now what should I think and/or do??

Hopefully you can give me a speedy response.

Thank you very much.