Internal server error when sending an email

[#1]

---

@MrZeno wrote:

I've done what you said about changing the authentication to none, and it didn't work. 

---

I do not believe that I suggested that - the authentication should be set to the same as the incoming server.

[#2]

@remikz / @jeffh / @MrZeno / @MRChambers 

Some of you have mentioned "Internal Server Error" but not specified which error code.  There are potentially two distinct issues here, which is why precise detail is always important.

• Internal error 4.3.2 relates to the absence of authentication credentials on the SMTP server for relay.force9.net - set authentication to use the inbound server's credentials
• Internal error 550 suggests that your credentials have been the object of service abuse
• The second might be 'disclosed' when the former is fixed

Sender Domain Rejected (black listed by local policy)

This issue can report as server error 550. It typically arises where a user's email address has been abused for the purposes of sending spam emails. It has nothing to do with server settings etc.

This requires intervention by staff to determine the cause of the problem and to issue advice to check your system for viruses and malware. Only after your system(s) have been affirmed to be clean can the black listing be lifted. As a precaution, you should change the password on the affected email address.

Add your details to this thread - Cannot Send Emails and send a PM to @Leanne_T

[#3]

Setting authentication resolved the issue for me.

Previously you didn't have to do this when connected to Plus.Net but it seems you do now. 

[#4]

@remikz 

The requirement for this going forward is in the migration FAQ.

@dave  / @plusnettony 

Can the requirement for SMTP authentication be included explicitly in the migration communications please.