Login to server relay.plus.net with username xxxxxxxxx+xxxxxx failed

[#1]

Using Thunderbird 68.10.0 I  have been getting the above message when  trying to send messages today via relay.plus.net (account and mailbox name blanked out)

Webmail works fine with same password, anybody else seeing this issue?

[#2]

I found the answer by turning on SMTP debugging in Thunderbird.

Apparently authentication is being rejected by relay.plus.net due to "poor reputation" of IP address.

I am currently using on my connection in Spain and have not had this problem before.

I am getting round it by using my mobile internet connection.

[#3 · Accepted solution]

On checking the IP address from my Spanish provider with spam bllacklists I found that "This IP address was detected and listed 4 times in the past 28 days" according to abuseat.org.

Interestingly this was the only blacklist the IP was on and it was accepted happily by the Hotmail mail relay.

Just in case someone else encounters this problem...

Problem solved

[#4]

Hotmail's acceptance of a blacklisted IP address is testimony as to why there is so much spam routed through hotmail relay servers.

Though clearly a slight inconvenience, when out side of the UK, there is good merit in sending emails via webmail.  Note that if you DRAFT emails on your PC and place them in the IMAP linked DRAFTS folder, you can then send them from a webmail session.

Abuse of email SMTP servers from overseas locations is a real security risk, which if not firmly managed would damage the reputation of Plusnet's relay servers to the inconvenience of the whole user base.