This requires set up in 2 steps – Using gmail to receive your domain email and then to send it out. 

You will need a quiet, undisturbed 10 mins to do it.  Best done from a desktop computer/laptop & to avoid any frustration, make sure you know your email password! (see right at the bottom for link to a youtube tutorial which you may find helpful)

Open up Gmail and go to Settings (gearwheel far right) > Settings > Accounts and Import >Check email from other accounts > Add an email account

Enter your full email address in the box in the window > Next > Import emails from my other account (POP3) > Next

Username: (your full email address)
Password: xxxxx
Pop Server: cloud304.thundercloud.uk Port: 995

Tick the checkbox ‘Always use a secure connection (SSL) when retrieving mail’
(the others are optional – best leave them unchecked)
Click ‘Add Account’

Gmail will connect with the server and will now ask. Would you like to be able to SEND MAIL from your domain email account using gmail. Make sure ‘Yes’, is selected, click NEXT

Enter your Business Name in the Name Box (this is so people you send to can see who it’s from). Then click ‘Next Step’

SMTP Server: cloud304.thundercloud.uk Port: 465
Username: (your full email address)
Password: xxxxx

Check the option: Secured connection using SSL (recommended)

(Make sure the port number is 465)

then click ‘Add Account’

Gmail will now send a confirmation code to your domain email to verify the set up.  (leave this window open)

If your Roundcube webmail is open, you can get the confirmation code from there and paste it into the window (that you just left open) to confirm (click verify)

If the email with the code is not showing in webmail, it may already have been imported into your gmail account so check the inbox there.

Once you have successfully entered the code and clicked verify, your domain email is now fully up and running through Gmail, so go to your inbox to check your mail. 

Use the gmail app for access on multiple devices.

There is a step by step visual instruction on YouTube which you may like to watch first: https://www.youtube.com/watch?v=ynpDaY6noMk There may be a very slight variation due to the gmail being a previous version and of course you need to use your own settings (above) but you should still find this visual instruction very helpful.