cant send outgoing emails from thunderbird error tt603

[oldfogie]

I use my talktalk email adress from thunderbird to send emails to a small group of people (around 20 in all) - never more than a few times a week.

This morning I'm getting an eror tt603

Here are my settings for the outgoing server - the user name is my talktalk email address.

[Gondola]

Excellent. Grateful thanks for confirming that all is back to normal.

[oldfogie]

Hi @Gondola as you suggested I've removed some recipients from the list as no longer current.

Tried it today and all seems to have gone well.

Thanks for your help

[Gondola]

Hi @oldfogie 

Is your mail sending restored to normal? My own checks tell me that mail sending to multiple recipients is working as expected. It would be useful to have your feedback and if not working then as much detail as possible on how you're using TalkTalk Mail and to what recipients and what send error message etc.

[Gondola]

Just a follow up from me to say I've been having a further look at this TT603 issue.

It seems to me that the spam protection process for sending mail is being triggered but not necessarily by the non availability of recipient mailboxes. So, the root cause I now believe is because the TalkTalk Mail SMTP servers are having trouble sending out mail to multiple addresses. Single addresses (both on platform TalkTalk addresses and off platform non-TalkTalk addresses) get sent without a problem, so long as the TT603 temporary restriction isn't already in place as that won't be relaxed until waiting for an hour.

I'll be reporting my diagnosis to TalkTalk Support but as it's a Bank Holiday weekend the full team will pick this up from Tuesday onwards.

[Gondola]

The way to troubleshoot a Distribution List when one or more recipients are rejecting the group mailing is to send to each recipient individually. Then you should see a delivery fail for those that are not, for whatever reason, accepting your mailshot.

[oldfogie]

Thanks Gondola, Looking back I dont see any message undeliverable reports, I cant try again - and if I could I'd be spamming my recipients.

I'll have to try again next time I need to send out a group message - or find a different way of contacting the group.

[Gondola]

If you're also seeing an error message "453.4.2.0 Too many recipients" then you need to check your list of recipients. Usually it means that one or more recipient mailboxes or recipient mail services are rejecting the mail. This is a not a permanent stop on sending at the moment but you do need to remove from the sending list those mailboxes that are either not available or that have marked your mail as unwanted or where the recipient mail service has rejected the mail.