Archived Forum Post

Index of archived forum posts


Sending Mail using SMTP through office365 is slow

Sep 30 '14 at 19:35

I am able to successfully send mail to on port 587 by setting StartTLS to true. However it's painfully slow (5-10 seconds). I'm guessing this might be a tar pitting method on Microsoft's part but I just wondered if there were any settings that could speed this up in chilkat. I'm just sending a test email with no attachments so I know it's not a bandwidth issue.

If you have any suggestions please let me know.

Thank you!

Accepted Answer

Todd, I use Office365 to send (tons of) email for several clients and they all experience slowness with the whole emailing process, regardless of the client used (custom, as for Chilkat or not).

Also, note that emails sent through this route appear to take much longer to be served by Office365's SMTP servers, than emails sent through Outlook/other MS products. There may be some prioritization going on.

I have noticed, clients using their own Exchange servers do not have this issue.

My workaround the issue has been to use Chilkat's SMTPQ, which queues the messages and returns to your flow immediately. This has added benefits, if for example MS' server is having issues (VERY common), you can use the queue sent log to review and resend as necessary.

Overtime I've learned to keep a copy of the sent messages and purge on schedule. This has allowed us to recover from few very sticky situations with client's emails. Having the copy prior to being sent is great.

Not to mention having all email logged so you don't have to. How many times have you gotten a user be SURE they have not seen the email? Unless you are logging yourself sometimes it is not easy to tell. Chilkat's SMTPQ takes care of it. -- I think this is a very underrated product.

-- Happy programming.