How emails are sent with Mergo?
Mergo uses the Gmail API to send emails and does not rely on an SMTP server.
If you want your emails to be sent by a specific SMTP server you can set up an email alias in Gmail and use that alias with Mergo.
See here how to set up an alias in Gmail:
https://support.google.com/mail/answer/22370?hl=en
And more info about how Mergo works with your aliases: