Hi Fred, 550 5.7.1 means that the client's spam protection rejected the email for some reason. You can contact the person either via phone/text or using a separate email account to let them know their system is rejecting your email. https://docs.microsoft.com/en-us/office365/troubleshoot/antispam/message-rejected-ndr > The sender has probably landed on a third-party anti-spam product's > signature list. This may be caused by nonstandard email practices such > as a failure to audit mailing lists. Recipients of these email > messages have previously submitted those email messages as spam to > their anti-spam product vendor. The vendor then added an identifier > that's unique to the sender to its anti-spam definitions. It's this > identifier that's now blocking the email. > > Most frequently, the detection is triggered by something in the email > signature. This might be a URL, domain name, or telephone number. > > We recommend that you confirm the cause by sending a test email > message to the same recipient after you completely remove the > signature. If the email message is delivered without issue, you can > confirm that a component or characteristic of the signature is causing > the blocked email. > Best, Sam ------------------------------------------------------------------------ Sam McClellan *Itabix, Inc* /One place for all things Web/ sam at itabix.com https://itabix.com Main - 413.587.4600 Toll-free - 877-7ITABIX (877.748.2249) On 5/27/2020 11:16 AM, Fred Levine via Hidden-discuss wrote: > > I’m wondering if anyone can shed light on this error message (Outlook > for Mac): > > host mx2.hc3579-74.iphmx.com [139.138.58.193] > > SMTP error from remote mail server after DATA: > > 550 #5.7.1 Your access to submit messages to this e-mail system > has been rejected > > I’ve sent multiple messages to the same address with no problem. > Suddenly they’re being rejected. > > Thanks, > > Fred > > Fred Levine > > Small Batch Books > > 493 S. Pleasant St. > > Amherst, MA 01002 > > 413.230.3943 > > > _______________________________________________ > Hidden-discuss mailing list - home page: http://www.hidden-tech.net > Hidden-discuss at lists.hidden-tech.net > > You are receiving this because you are on the Hidden-Tech Discussion list. > If you would like to change your list preferences, Go to the Members > page on the Hidden Tech Web site. > http://www.hidden-tech.net/members -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.hidden-tech.net/pipermail/hidden-discuss/attachments/20200528/87aa5560/attachment-0001.html>