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We can send mails across the network from 1 server to another via a centralized smtp server. However, the we get a synchronization error on the server randomly.

So for example if we send a simple mail 6 times the 3rd one fails with a synchronization error. When we look at the network packet we have


C:QUIT -- This for some reason is called before the smtp server processes the request.

enter image description here Any clues why this with happen.

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You'll need to give us more details on your setup. I've never heard the word synchronization used in relation to SMTP. What exactly is being synchronized and how? – joeqwerty Mar 20 '14 at 15:47
Added image, please check image in question. – Dreamer78692 Mar 20 '14 at 17:32
Are you waiting for the "220 - SMTP Service ready" before attempting to send a message?… – Peter Mar 23 '14 at 8:22
It looks to me as if is taking a long time handling the recipient address validation, as seen by the delay at the RCPT TO request. You need to provide the server log of the transaction from – Matthew Ife Mar 23 '14 at 9:58
up vote 2 down vote accepted

As we can see in your log,

your server at xx.18.199 did not answer the RCPT TO: in 30s, so a timeout must be setup at the xx.31.37 client which makes it send a QUIT after 30s without answer.

The obvious fix is to increase the timeout on the client side.

The less obvious fix is to find out why it takes so long to process the RCPT TO:. Maybe your directory is very slow ?

If you provide more details about your configuration and the email addresses which cause a response time greater than 30s it will certainly be possible to dig further and find out what's happening.

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