User claims to have lost 1400 BTC after clicking malware link from a malicious electrum server.

Regardless of whether or not this is true it serves as a good reminder to use up to date software.

(This was patched in 2019.) https://github.com/spesmilo/electrum/issues/5072#issuecomment-683374289

Install Electrum from the official source http://electrum.org  & Verify signatures

Ask people you trust & check multiple hard to forge online sources e.g. first slide of presentation at a bitcoin conference on official YouTube channel & http://electrum.org  & Devs twitter

Example of an electrum phishing popup.

This is how you verify the signature:

https://electrum.readthedocs.io/en/latest/gpg-check.html

The key thing is to verify the key
(6694 D8DE 7BE8 EE56 31BE D950 2BD5 824B 7F94 70E6) truly does belong to Thomas Voegtlin.

As mentioned, there are many ways to do this and you should use more than one to be sure

For example at 3:22:30 in this conference Thomas V shows his key which you can see matches

Here is a good thread by @_benkaufman that explains how this phishing actually works https://twitter.com/_benkaufman/status/1299971319430352897?s=20