My outgoing mail isnt working it keeps giving the same error.
This has been happening for the past two days, Can someone please help me fix this?
Thank you!
Regards
– but I can see you have a v9 license. Don’t install v10 over it without upgrading first.
Hello, I’ve the same issue on eM Client version 9 Pro, for which I paid for a license. Do you mean that the issue can’t be fixed on version 9 Pro and I must necessarily upgrade to version 10 ?
If I’m not wrong the upgrade from v9 to v10 isn’t free.
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Version 9 uses AirSync for sending emails, so if you’d like to keep using version 9, you can change the sending protocol to SMTP instead, and disable AirSync calendar and contacts. Here’s the registry configuration that will do that:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\eM Client]
"UseAirSyncSendMail"=dword:00000000
Copy this in a text file and save it as a .reg file, then run it. Then go to Menu > Accounts and disable AirSync under Services.
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Thank you for the detailed instructions. I did as you suggested then I sent a e-mail from my Outlook account to my GMail account by using the attached SMTP settings. I didn’t get anymore the AirSync error but it failed anyway because I got a different error, which I’ve attached. After changing the Security Policy to “Use SSL / TLS if available” I sent another e-mail and it was successfully sent (and received) but after that I noticed that the Security Policy automatically changed to “Force usage of SSL / TLS” . So for me the issue is solved but I wonder why the Security Policy setting I used previously (Use SSL/TLS on special port (Legacy)) doesn’t work anymore. Also I don’t understand why the setting “Use SSL / TLS if available” automatically switched to “Force usage of SSL / TLS” after sending a e-mail.
Lastly it’s not entirely clear to me which is the difference between “Use SSL / TLS if available” and “Force usage of SSL / TLS”
I didn’t get anymore the AirSync error but it failed anyway because I got a different error, which I’ve attached
For eM Client V6-V10.2 SMTP Port 587 you select - Force usage of SSL/TLS
For eM Client V10.3 or higher SMTP Port 587 you select - "Use STARTTLS (Always)”
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About security policies I also tested “Use SSL/TLS on special port (Legacy)” with port 465 but the e-mail simply wasn’t sent, staying in “Outbox” , I didn’t get any error.
I also tested “Use SSL / TLS if available” with port 25, the e-mail was sent and received but after that the security policy switch to “Force usage of SSL / TLS” (port 25) so it seems you are forced to use this setting and it doesn’t matter which port is entered.
About security policies I also tested “Use SSL/TLS on special port (Legacy)” with port 465 but the e-mail simply wasn’t sent, staying in “Outbox” , I didn’t get any error.
Port 465 will only work if the SMTP Server supports that. Outlook needs SMTP Port 587
Note: If you have modified the Registry setting @Kim_Fisher advised further up “make sure you shutdown and reboot your computer” or it wont send.
If you have rebooted and are using Port 587 with Force usage of SSL/TLS then and have disabled AirSync under Services, then “move the email stuck on the outbox back into the drafts folder” and open it and try sending it again.
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I haven’t rebooted yet. I’ll do now, thanks.
Thank you very much for the clarifications. After the reboot It seems there aren’t any differences anyway. I mean I manage to send e-mail like I wrote in my previous posts, before rebooting the PC but I must necessarily use the setting “Force usage of SSL / TLS” (I sent e-mail successfully with both port 587 and port 25). Anyway I still don’t fully understand the difference between “Use SSL / TLS if available” and “Force usage of SSL / TLS”
Indeed, just as experiment, I configured Outlook SMTP on Thunderbird as SSL / TLS on port 465 but the verification failed. I had to set STARTTLS on port 587 for a successfully verification. I notice that STARTTLS security policy is missing in eM Client Pro version 9.
Also I just found this article POP, IMAP, and SMTP settings for Outlook.com - Microsoft Support
For SMTP it reads SMTP port: 587 SMTP encryption: STARTTLS so Outlook doesn’t use anymore SSL / TLS ? I’m rather confused 
If this is the case, what the setting “Force usage of SSL / TLS” in eM Client v9 Pro really does if that security policy isn’t supported anymore in Outlook ?
As i said for eM Client V9-10.2 you use Port 587 you select - Force usage of SSL/TLS
I know but reading the article I posted above it seems that Outlook supports only STARTTLS not SSL/TLS so I’m wondering what “Force usage of SSL/TLS” really does.
“Force usage of SSL/TLS” & "Use STARTTLS (Always)” are the same security policies.
Its just now in V10.3 or later its standardised and called "Use STARTTLS (Always)”.
So for V9 Pro as you have for Outlook you use Port 587 you select - Force usage of SSL/TLS
Thank you, this clarifies all. Maybe implementing “STARTTLS” also in eM Client version 9 would avoid some confusion on the matter, in my opinion, also because it seems to me that STARTTLS is less secure than SSL/TLS. STARTTLS vs SSL vs TLS Explained in 5 Minutes
In conclusion “Force usage of SSL/TLS” and “STARTTLS” can’t be the same thing.
No need to implement STARTTLS in V9 “as both settings are as secure as each other”. As mentioned previously “Force usage of SSL/TLS” was used like that up to eM Client V10.2.
Quote:
Forcing the use of SSL/TLS (properly known as TLS, or Transport Layer Security) is considered highly secure and is the standard practice for modern internet security. It ensures that data is encrypted during transmission, rendering it unreadable to eavesdroppers.
Apart from the security issue, they are still different protocols and indicate “Force usage of SSL/TLS” when only the “STARTTLS” protocol is applicable, as in the case of Outlook, is misleading, in my opinion. Anyway case closed for me. I stand by my opinions just as you stand by yours.
If you want better security sending in V9 or V10 “between you and the other party”, you can optionally send an encrypted email message using a PGP Key. Some users do that.
“eM Client PGP Documentation”
V9
https://www.emclient.com/webdocumentation/en/9.0/emclient/default.htm#E-mail/PGP.htm
V10
https://www.emclient.com/webdocumentation/en/10.0/emclient/default.htm#E-mail/PGP.htm
Quote:- from the above link.
“PGP is a public key encryption program that has become the most popular standard for email encryption - it follows the OpenPGP standard (RFC 4880) for encrypting and decrypting data”.
“Each user has an encryption key that is publicly known and a private key that is known only to that user. To send encrypted messages you need the public key of your recipient. To decrypt a message sent to you, you will use your private key to decrypt it”.
See the below eM Client webpages on how to setup PGP encryption.
“Email Encryption and Digital Signature”
Quick guide to email encryption and email digital signatures in eM Client
https://www.emclient.com/email-encryption
eM Client also has its on Public encryption key directory you can u/l & manage your public keys.
“What is eM Keybook”
https://support.emclient.com/index.php?/Knowledgebase/Article/View/221/6/what-is-em-keybook
Quote extract below from the above link:-
“eM Keybook is a public encryption key directory managed by the company eM Client.
It’s an online service where you can upload and manage your public keys so anyone can easily send you encrypted messages and you can easily get public keys of the recipients you want to send encrypted messages to”.
Thank you but it’s too complicated for me. I just need a e-mail client for my daily needs and until now emClient has proven effective for that purpose.
Sounds like it 
I’m in the same boat.