Thunderbird Greenby Identities

[#1]

After 3 weeks of chatting to Greenby;'s AI bot, which is very good, I am back in action 

But one surprise - I use Thunderbird identities and have been told that, for security reasons, I have to duplicate any and all Tbird identities in Greenby as aliases of the email post box.

[#2]

@BS6600 I also use Tbird identities, and have not come across any problems so far.

My understanding is that aliases affect which mailbox an incoming mail is put in, and Tbird identities enabled you to send an email from the specified address. If you want a reply from an identity to come back into the same mailbox, then an alias seems a good idea, unless it is a catch-all mailbox. 

What question or problem provoked the bot to suggest you needed aliases for security reasons?