[2Gkashmiri]

i will give my 2 cents.

i use mailinabox and it works good enough for me. I can generate aliases at any limit and without any burden. Now, what you are describing is the same in mailinabox. the alias is merely a "receiving" alias. you cannot send from that.

what i found out was, how i can bypass this is by deleting the alias, then creating a new user with that email. a new email inbox is created. then you send that email whatever you want to send.

then you can delete the user and create alias once again and you are back to square one.

i know, its tedious process but it works for me. since apple probably wont let you create accounts with those disposable emails, then they should allow sending from aliases.