Description of the problem

When setting up the email service via:
Settings -> Outgoing Email
or attempting to send an email from the CP:
Tools -> Utilities -> Send Email
the validation for the Email field does not recognise an address such as globalsecurity@pmb.ox.ac.uk as being valid

How To Reproduce
Steps to reproduce the behavior:
Go to either Outgoing Email or Send mail and attempt to use globalsecurity@pmb.ox.ac.uk as an email address.

Error Messages

This field must contain a valid email address

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