@sruba @delta more than 150 is not recommended, see https://delta.chat/en/help#how-many-members-can-participate-in-a-single-group

plus, there are "channels" upcoming, they can handle a far larger number of recipients

@anon_4601 @dansup #deltachat does not require a phone number nor you have to provide your address nor a SIM card is required.

you can use it even without a phone.

it uses SMTP/IMAP under the hood, with a random address. nothing is persisted on the server, for metadata, see https://delta.chat/en/help#message-metadata