Email functionality overall is working fine.
However, if a Share request is initiated (one that requires moderation) that specific email will not come through, throwing:
Failed attempt 1 sending mail to recipients: access.requests@domain. Mail Subject: Tiago Duarte wants to share 'blah-blah' with Crazy Johnny. Error: SmtpException while sending email: System.Net.Mail.SmtpException: Mailbox unavailable. The server response was: 5.7.1 Client does not have permissions to send as this sender at System.Net.Mail.DataStopCommand.CheckResponse(SmtpStatusCode statusCode, String serverResponse) at System.Net.Mail.DataStopCommand.Send(SmtpConnection conn) at System.Net.ClosableStream.Close() at System.Net.Mail.SmtpClient.Send(MailMessage message) at Microsoft.SharePoint.Email.SPSmtpClient.Send(MailMessage msg) at Microsoft.SharePoint.Email.SPSmtpClient.TrySend(MailMessage msg)
The email from the
Send an email invitation checkbox is sent perfectly. Grant or decline actions emails are also sent.
Note: This has been working fine for over a year until last week.
Attempts: tried multiple outbound
from addresses, but it doesn't seem to even matter, always throwing the same exception