Plan better back to school email campaigns with practical timing and content tips, inspiring brand examples, and ready-to-use email templates.
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Switching your email account to Microsoft 365 can sometimes cause unexpected issues, especially when sending emails via SMTP through third-party apps like Mail Designer 365. Many users report that after the migration, their newsletters or other outgoing emails fail to send, even though login credentials remain correct. This article explains why this happens and provides you with a straightforward fix to help get you back on track.
Why Microsoft 365 SMTP Access May Fail
Many Microsoft 365 plans no longer provide traditional SMTP access in the way third-party apps expect. In some cases, SMTP is completely blocked, or it requires complex OAuth2 authentication. The classic login method, using just a username and password for SMTP, IMAP, or POP3, is often disabled by default after migration. This means that even if your app password is correct, third-party apps may fail to authenticate with Microsoft’s servers.
How This Affects SMTP Sending in Mail Designer 365
Mail Designer 365's SMTP send feature relies on a working SMTP connection to send emails. If your SMTP connection is blocked or requires a protocol the app doesn’t support, the login to the mail server will fail, and sending emails will not work. Users often encounter error messages indicating authentication failures, which can be confusing if email credentials work in other apps like Apple Mail or Outlook.
An Alternative to SMTP in Mail Designer
If SMTP sending is no longer available with your Microsoft 365 account, Mail Designer 365 offers a built-in sending service that avoids these limitations altogether.
Mail Designer 365 provides two integrated sending options:
- Direct Send – ideal for 1:1 emails and smaller recipient groups, similar to traditional SMTP sending
- Campaign Sending – designed for marketing newsletters and larger email distributions
Both options allow you to send emails without relying on your email provider’s SMTP access, making sending more reliable and easier to maintain as provider requirements continue to change.
With Mail Designer 365 Direct Mail, you can send professional HTML emails directly from your Mac without relying on SMTP
Good to know: All Mail Designer 365 design plans include a base sending allowance, so you can get started right away and send up to 20 Direct Mails a month, at no additional cost.
Why Use Mail Designer 365’s Sending Service?
- Custom domain authentication: Support for DKIM, SPF, and DMARC helps ensure your emails are properly authenticated and trusted by receiving servers.
- Improved deliverability: Modern sending infrastructure helps your emails reach inboxes rather than spam folders.
- Less dependency on email providers: You’re no longer affected by changes to Microsoft 365 or other providers’ SMTP and authentication policies.
By using Mail Designer 365’s sending service, you can continue sending professional emails and newsletters with confidence, even as email platforms evolve and restrict traditional SMTP access.
In this email promotion, JackThreads have opted for the classic Halloween sale. 70% off is impressive and will instantly pique readers' interest. The funny pumpkin graphic is also a clever way to grab the attention of the reader and get them in the Halloween spirit.
This email by thredUP is a bit less on the scary side, but still seriously cool. Dressing up and having fun is what Halloween is all about so these DIY costume ideas are ideal for kids and parents alike. The CTA links are also easy to locate, making shopping for the perfect costume even easier!
Graze are making us hungry with this snack-themed Halloween email! Concentrating on the health benefits of pumpkin seeds is smart at this time of the year and gets readers hungry to find out more about this nutritious snack. The little pumpkins scattered throughout the design also help add to the seasonal theme without going overboard.
Boohoo also get creative with GIFs in yet another trick or treat inspired email design. Although the rest of the email is pretty simple, the main eye-catcher is the heaven vs. hell GIF animation at the top of the design which instantly makes the theme clear.
This email from Sainsbury's is yet another example of how you can use your Halloween email campaigns to offer customers practical tips and advice. The email has a great balance of text, images, fun graphics and CTA buttons.
Land's End have pulled out all the stops on this email design. The 31% offer paired with the spooky ghost and the "Boo" discount code makes it no secret what the theme of this campaign is...
We've found yet another food-themed email! Pizza Hut have embraced the Halloween theme with this vibrant email design. The CTA is super tempting and makes the reader want to click straight away to discover their exclusive deal.
Kohl's have hit the nail on the head with their Halloween themed discount draw. There is a lot going on in this promotion. As well as the mystery discount offer, they also offer money off a threshold spend. All of these offers go along with the exciting nature of Halloween and encourage readers to get shopping.
This email by Unidays is a similar concept to the previous email. In this example, there is even more of a sense of mystery thanks to the question mark graphic. The glowing green CTA button is also super prominent and entices the reader to click.
Look away now if spiders aren't your thing! This design by American Eagle Outfitters is pretty simplistic, but perfectly captures the Halloween theme thanks to the spooky spiderweb graphic. Also notice the little bat icon in the top left corner which they've swapped their usual eagle logo for. Just small changes like this can be super effective during the holidays.
