Our Bank "A" suffered a major DDoS attack recently. My non-techy partner, upset, declared were moving to Bank "B". I pointed out that Bank B had also been target of DDoS attacks so we would be moving banks only to face the exact same issues. Point being you may move to a different service provider (email, banking, whatever) to find the new one has the same problems anyway.
Is it really worth the hassle to move to another provider/self-hosted server for such a temporary problem?
Moving to another provider would mean to set up a new account, and usually the free tiers won't allow to use your own domain. So you would be locked to a new provider where you could face the same problems.
Temporarily moving to a self-hosted server would be an option, but probably just to receive emails during this time. You'd have to set up your certificate, and optionally DKIM, DMARC, SPF or whatever is required to ensure that your sent emails arrive properly. I can't imagine self-hosting email being something which won't give you a hard time every now and then.
Generally yes, I am in favor of owning your email-domain, but then using it with a professional provider like mailbox.org unless you really know enough about the topic.
But in this case, where the issue is a DDoS attack, I wouldn't do anything, since all undelivered email will be re-sent at a later time.
Or less hassle than completely moving over to a competitor (terrorists win in that case, to use counter strike terminology): add a backup MX record, perhaps to a small vps that just forwards mail to the real server with no retry timeout.
Are there any mail admins in the comments who could propose an smtp daemon & configs that would store all mail for a domain and wait indefinitely to forward it on? I think there's a lot of users/businesses who would like to implement this.