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EC-Nordbund / denomailer

A SMTP-Client implementation for deno (to send mails!)
https://deno.land/x/denomailer
MIT License
50 stars 16 forks source link

some errors should not result in a full mail sending abort #7

Open mathe42 opened 2 years ago

mathe42 commented 2 years ago

check wich errors will have to result in a message abort and wich should lead to modified mail config

For example:

If an email adress doesn't exists this is sometimes detected by the smtp server (for example when domain doesn't exist). If it currently detects that denomailer will stop the complete mail from sending (even mails to 1000 adresses but 1 is not valid).

if you have use cases and suggestions for specific error types please share!

suchislife801 commented 2 years ago

According to RFC 5321 Section 3.3 you either get a 250 OK or 550 NO SUCH USER.

Now, the 550 NO SUCH USER will only be returned for emails that belong to the same server you are sending emails from.

If the destination email address is wrong or simply does not exist, BUT DOES NOT BELONG TO the sending server, you will get a 250 OK regardless. That's because smtp servers from one provider do not talk to smtp servers from other providers.

Send a 1000 emails. Get the bounce backs because you have no other option. Remove the bad ones from the list. Have a better list.