How are you telling your guests if you are canceling or rescheduling?

We emailed everyone

I made a Facebook group and added all the invited guests with an announcement of postponing

We split our list - my family/friends and his. We texted people or used FB messenger. I did not mass text but said the same in each individual text: We wanted to let you know we’ve decided to postpone our wedding. We’re working with the country club reception site to get a new date in September or October. We will send new invitations out this summer. Love and kisses. Stay safe and healthy. Those that we didn’t have information on like mil neighbor I told her to do.

View Quoted Comment I never thought about that idea, thanks Iris for your input!!

View Quoted Comment That’s what I am leaning towards too, thank you Leslie for your input!! Best wishes.

We called & texted immediate family and bridal party. For everyone else, we emailed and also posted on the wedding website.

View Quoted Comment That’s a great way to go, thanks for your input Sylvia!

I texted everyone as soon as we had the new date, updated my wedding website, and then got "Business Postcards" on Vistaprint and customized the text to give all the information. It cost me $40 for 250 (I only needed 140, but it was either get 100 or 250 haha). I then made a Facebook status after I mailed the postcards to let guests know to get in touch if they didn't get a card! Postcard postage stamps are 25 cents cheaper than regular postage as well, and USPS can ship them to your house! I paid about $70 for everything!

Traditional etiquette is that you use either a casual note form ( modern, mail or email) or a phone call to cancel or postpone a wedding or other major event after any save or find all invitation goes out. Something that struck me in reading etiquette books on this, was that hosts are expected to do this personally, except in the case where a death is involved , or a wedding. When it is seen as proper for other family or helpful friends to divvy up a list for phone calls, notes/emails.
I cannot imagine wanting to talk to an entire guest list , as posters above said. And accepted good manners say this can be delegated to save distress . Same as when you cancel a shower or christening at the home of mother and child because baby is ill or died.
Texts are generally frowned on because most messages are not searchable, nor is there a subject line, as an email has. Without subject lines, it is hard to go back to a text you think was 20-40 days ago, or 3 months, to check something. So general etiquette here seems sensible.