Transcribe From: e-mail regexp does not support TLD-s longer than 4 char

Description:

The transcript From: email gets parts cut off or mail is not sent when TLD should be longer than 4 char (like .casino, .luxury, .photo, .photography, .consulting, etc)
Part is getting cut off from something like rocketchat@subdomain.dmn.photo and ends up being rocketchat@subdomain.dmn

The regexp to check the e-mail does not support for TLD-s that can be longer than 4 characters due to this issue it cuts off the last part of "From: " if using something like subdomain.domain.photo.

Steps to reproduce:

1. Set up e-mail with longer than 4 char TLD
2. Send transcript
3. Check From: address

Expected behavior:

Full From: address in e-mail headers

Actual behavior:

TLD is being cut off if domain part is short like 3-4 char.

Server Setup Information:

Server info irrelevant, as issue is in code base from it's creation commit.

• Version of Rocket.Chat Server: 3.14.1
• Operating System: Debian 11
• Deployment Method: https://docs.rocket.chat/installing-and-updating/manual-installation/debian
• Number of Running Instances: 1
• DB Replicaset Oplog: Enabled
• NodeJS Version: 12.18.4 - x64
• MongoDB Version:4.4.6
• MongoDB Engine: wiredTiger
• Commit Hash: 6bfd1ac9c9
• Commit Branch: HEAD

Client Setup Information

Client info irrelevant, as issue is in code base from it's creation commit.

• Desktop App or Browser Version: Firefox 88.0.1, Opera 76.0.4017.123, Chrome (Latest), Mac Desktop app, Windows Desktop app
• Operating System: Windows 10 / ArchLinux / MacOS Big Sur

Additional context

Errors located here in regexp!
https://github.com/RocketChat/Rocket.Chat/blob/157b882d38b34b7b79dea527316554fe33f70891/app/livechat/server/lib/Livechat.js#L994

https://github.com/RocketChat/Rocket.Chat/blob/develop/app/livechat/server/lib/Livechat.js#L997

https://github.com/RocketChat/Rocket.Chat/blob/157b882d38b34b7b79dea527316554fe33f70891/app/livechat/server/lib/Livechat.js#L1079

https://github.com/RocketChat/Rocket.Chat/blob/develop/app/livechat/server/lib/Livechat.js#L1082

Relevant logs:

N/A
It is code error, location pointed out to you above.

Inspect the e-mail regexp in app/livechat/server/lib/Livechat.js around lines 997 and 1082. Reproduce the transcript with an address such as rocketchat@subdomain.dmn.photo and verify that the completed change preserves the full address in the From header for TLDs longer than four characters.