Github dislikes email "aliases" so much that they will shadow ban your otherwise normal activities for months, and once flagged, support will request not only a "valid" email domain but also that you remove the "alias" email from the account completely.
I had the same issue with my Anonaddy alias, I just made an alias using my domain name and works fine now. It's unfortunate that so many project are on shithub.
GitHub is owned by Microsoft and Microsoft also hates email aliases. May I recommend Port87. Microsoft and GitHub both accept the tagged addresses you use with Port87.
Github is unfortunately the premier platform for collaborating with others to build FOSS. Until alternative forges support federation, any other forge is usually a dead end.
The pull request model Microsoft GitHub force on users ends up being a colossal waste of everyone’s time & it’s the only model offered. It’s also a social media platform which encourages star hacking, READMEs that are actually RENDERMEs, focusing too much on making one’s graph green, etc. that are bad for project quality & mental health IMO. This doesn’t sound like a “premier” platform but the result of lock-in & network effect. The way to break is to go host elsewhere… & since Git is a distributed version control system, this should be encouraged.
Not true, there is a distinction between your reply address and any secondary addresses you have configured on the mailbox. Still, as far as I know that's not something they should be able to see from outside your email server. You are setting up aliases on your own server right, not using some third party as an intermediary? Using a third party intermediary would possibly be something they can see from the delivery routing.
It's most likely that this is just them shitting on you for using an "untrusted" provider. Most big sites and email providers are really getting stingy lately with who they'll accept email from and what is accepted as a valid email domain. There's also a big push for properly configured SPF and DKIM records that aren't set to allow spoofing sender domain. It's combining to cause a lot of issues for self hosters lately, and also for companies that have vendors who insist on sending email from the vendor's servers but appearing as from the company itself.
Likely that they don't "trust" your email provider, but there's a lot of strange A/B testing going on behind the scenes of that data harvester.
Setting up a dedicated spare gmail or outlook account solves that issue.
Registering a "cell number" helps too, but it's hard finding a service that offers "free texting numbers" that isn't set up in a way that they can see that it's just one of those services. Wish I remembered what finally worked for me.
Lastly, if you're using a modified Discord app or desktop install, be sparing with the non-standard features. That can flag you sometimes too.
For most servers though, I find it easiest to just access them in browser as a not signed in guest.
I think Google Voice still gives out a free phone number as long as you tie it to your actual phone number. I used it for Craigslist all the time years ago to avoid giving out my actual number
Are you using 2FA ? With some services (Not Discord but others) I found out that when 2FA is enabled I will not have to suffer endless amount of CAPTCHAs and what not.