This is related to both Zohomail and Zeptomail. Because Im not sure what would happen to Zohomail based on the situation im about to explain.

I'm going to use examples to try to explain the dilemma I'm in.

My client has an organization that was created with their gmail account for example: example@gmail.com

My client website is https://example.com

I want my client to invite me into their organization, so im thinking of creating an email account called: webmaster@example.com that I would have access to(as their developer) and that they can invite into the organization.

The thing is, what would happen in the future if I decide to connect their example.com domain to the organization? Especially if they want to move their current custom email service to Zoho Mail? 

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I'm asking this because I first told them to invite my email to their Zeptomail account as an "Engineer" so that I can set it up for them, but when I tried to accept the email, it said I was already part of an organization (my own, since I use Zoho as well) so I couldn't accept the invite.

So I'm wondering what would happen in the future if I decide to bring their email or other services to Zohomail and decide to attach it to their domain example.com and then start creating email accounts like info@example.com from within Zoho.

Would the webmaster@example.com email that was invited into Zeptomail still be able to access Zeptomail?