I did fly during the disruption period (had a bag delayed), and my email had an extra paragraph under the "how to claim" section:
Our phone lines and social media channels are extremely busy at the moment. We don’t want you to sit and wait, so recipients of this letter can email us their claim number and historic booking reference (or flight dates and surname) once logged online to our temporary inbox, [XXXXX] and we will endeavour to expedite your request. Please include your claim reference number in the subject line of your email and your booking reference, flight details and surname in the body of the email so that we can verify you.