I always suggest using the Default Email transport method:
To ensure emails are sent to your members, you will want to notify the most popular email providers using their bulk email notification. This will whitelist your forum domain to ensure emails go to your members.
AOL
https://postmaster.aol.com/trouble-ticket
Google
https://support.google.com/mail/contact/bulk_send
Microsoft (hotmail and msn.com) - requires Microsoft account
https://support.microsoft.com/en-us/supportrequestform/8ad563e3-288e-2a61-8122-3ba03d6b8d75
Yahoo - Requires Yahoo account
https://postmaster.verizonmedia.com/sender-request
To ensure emails are sent to your members, you will want to notify the most popular email providers using their bulk email notification. This will whitelist your forum domain to ensure emails go to your members.
AOL
https://postmaster.aol.com/trouble-ticket
https://support.google.com/mail/contact/bulk_send
Microsoft (hotmail and msn.com) - requires Microsoft account
https://support.microsoft.com/en-us/supportrequestform/8ad563e3-288e-2a61-8122-3ba03d6b8d75
Yahoo - Requires Yahoo account
https://postmaster.verizonmedia.com/sender-request
