Hi, 1.) How do I configure zoho mail with ISPConfig3? Thanks https://www.zoho.com/mail/help/zoho-smtp.html https://www.zoho.com/mail/help/imap-access.html SMTP Configuration settings for Zoho Mail - SSL Outgoing Server Name: smtp.zoho.com Port: 465 Security Type: SSL Require Authentication: Yes. Email address should match the email address/ aliases of the account, for which the authentication details are provided. SMTP Configuration settings for Zoho Mail - TLS Outgoing Server Name: smtp.zoho.com Port: 587Security Type: TLS Require Authentication: Yes. Email address should match the email address/ aliases of the account, for which the authentication details are provided. You may require Application Specific password to set up the account in other devices, if Two Factor Authentication is enabled for your account. Relaying disallowed: When you send emails from other software, if the email address you specify does not match the email addresses in the account for which authentication details provided by you, you will get the 'Relaying disallowed' error when trying to send emails through the servers. Generally, it may happen when you use a default address as sender (in a coded program), or when you have mistyped the email address section in the configuration. You will be able to receive emails, as only the authentication will be required for syncing emails. Only when you send emails, the email address with which you send is matched with the credentials you provide for the outgoing server. Hence correcting the email address would resolve this issue. When you send emails via SMTP client, if the email address you have entered does not match the email address for the account details provided, the client will not be able to send emails and will get a Relaying disallowed. Relaying disallowed when using Outlook Calendar and Mail: When you directly forward Calendar events from Outlook, by right click, the 'Relaying disallowed' error will occur, as the event invitation will be sent using the organizers email address, which cannot be completed due to authentication mismatch. Hence we suggest you to use the Right Click, Forward as Attachment for the events to avoid this error.