Email Tidbit

[Gary Beene]

Using Outlook I put my address in TO two times, but I only received the email once.

In a second test, I put my email address in TO and in CC, I only got the email once.

I might guess the that Outlook client is programmed not to send the email but one time, no matter how many times it is found in TO.and CC.

Didn't know that.

[Paul Dixon]

Perhaps the message is sent 2 times but Outlook recognises the second receipt as identical to the first receipt so ignores it.

[Rod Macia]

Very often the email servers are setup to remove duplicate email addresses, if they are part of the same send.

They are also setup to detect cyclic emails. (emailA set to forward to emailB and emailB set to forward to emailA)

[Gary Beene]

Howdy, Paul and Rod!

Thanks for the replies.

I was using SocketTools to write an email client and in my version, if I put an address in TO two times, the recipient got it twice. That's what got me to trying it in Outlook.

[Stuart McLachlan]

Howdy, Paul and Rod!

Thanks for the replies.

I was using SocketTools to write an email client and in my version, if I put an address in TO two times, the recipient got it twice. That's what got me to trying it in Outlook.

Was your SocketTools acting as :
an MTA (i.e. sending through the same server as Outlook does using a Port such as 587 )
or
an SMTP Server (sending directly to the recipients mail server on Port 25)?

[Bud Durland]

I might guess the that Outlook client is programmed not to send the email but one time, no matter how many times it is found in TO.and CC.

That guess aligns with what I've observed over the years troubleshooting mail on our in-house server.

For the folks who've never delved into programmatically sending mail, the "To:", and "CC:" are really just presentation layer fluff for the human. When the client greets the mail server the conversation is basically "Hey, I have mail to send, here's the list of people it's for". That list is dynamically built by the client program based on what you entered. All my programs use a wrapper I built for Socket tools, and one of the functions it does is de-dupe that list.

[Mikael T]

Hi Gary, just to confirm your findings.

I did the same test with my version of Outlook and Yes only one of the emails was delivered.

Might be a stupid question, but how often do you send an email where the recipient and the copy is to the same address?

/Mikael

[Gary Beene]

Howdy, Stuart!

In the case where 2 copies were emailed, I was using webhero.com - not the same server that MS Outlook uses.


Howdy, Mikael!

Never! I was just running a test where I wanted to see what happens and so I used my [email protected] email address in both places so that I would not have to log on to 2 different accounts to see the results.


Howdy. Bud!

Yes, now that I know my email client that uses webhero.com server does not dedupe, I'll have to add a function to do that in my client..