Error 550

[MichaelMorris13]

I've suddenly started getting error 550 when trying to send emails via a third party app (OE Classic)m webmail works fine. I'm sure it's something at the ISP end. Any help?

[WSH]

You’re right.  500 series errors are at the server end.  (400 are at the user end).

550 can mean a whole lot of things but boils down to mail undeliverable.  Many reasons for this, unfortunately.  For example, it could be the address no longer exists, or you’ve made a mistake entering it.  It could also be that the server believes it to be spam and so has rejected it. 

Edit:  A though has just occurred.  I have heard that if you only have basic BT email, instead of the premium, it only lets you use web mail and will not allow the use of a third-party mail client.  Not sure how accurate that is, as I don't use BT mail.

[MichaelMorris13]

Thanks very much for that feedback. This has happened previously & seemed to "magically" start working again. I've got 2 email addresses, both of which have this problem, as does my wife's email address. I've just used Thunderbird & that worked fine. Mystery continues.................... 

[gg30340]

Are you presently a BT Broadband customer or are you paying for your email through a BT Premium email account or did you migrate to EE Broadband?

If none of the above your email account may have been downgraded to a BTMail Basic account which can not be used with an email client or email apps.

See link

https://www.bt.com/help/email/bt-email-products

[MichaelMorris13 · Accepted solution]

Thanks all for your helpful feedback, none of which resolved the problem (sadly) but as mentioned in one of my posts my email ability has "magically" resolved (happily). Once again thanks for all the help/feedback.