Even under the best conditions, my package deliveryman can’t seem to find my front door. When I complained to the carrier, the person on the line told me that it could possibly be due to temporary or seasonal help that was kept on the payroll to patch a gap in permanent staff. She candidly explained that for the less motivated of parcel carriers, the rule of thumb is, “If you can see the front door from the street, don’t bother leaving the truck.” I can go on and on about my package delivery woes, but the point I’m trying to make is: like lazy mailmen, email has rules when it comes to whether or not that packet hits the porch. Lucky for us, the rules are a bit clearer than those followed by seasonal carriers.


At any given moment, there’s a lot going on in a mail server. To put it simply, mail servers are constantly parsing messages, deciphering them, and passing them to the correct mailbox. When you try to pass a large attachment through them, they take longer and this can sometimes hold up the entire queue. Because of this, almost every mail server has a maximum attachment size criterion.

By default, Microsoft Exchange allows an email attachment of 10MB. In a world of high-speed internet that gets faster with every passing year, that’s pretty miniscule, but to a mail server, it’s gargantuan. Even Google’s Gmail, a service belonging to a massive super-corporation with boundless resources, has an attachment limit of a mere 25MB. Some mail providers get around this by integrating a behind-the-scenes file transfer protocol for internal email (Gmail account to Gmail account), but mail sent and received externally will typically still have a hard cap on attachment sizes.

Most documents typically fit well below the size threshold, but larger pdf documents, images, or spreadsheet files can bloat beyond the limitation. The preferred solution would be to not send these files through email, opting instead for cloud-based file hosting like Dropbox or the more complicated solution of an FTP service. If it absolutely has to get through a mail server, splitting the file into smaller ones and sending them individually or compressing them into a zip file can sometimes sneak it through the restrictions.


Even if your attachment fits under the size restraints, it may be blocked for another reason: its extension. A file extension is the .xls or .doc that you see buried at the end of almost every filename. It simply exists to tell the computer what program it will need to use to actually read the file.

Virus infections are frequently transmitted through attachments, so it’s in a mail server’s best interests to take a close look at them. Files of particular interest are executables (.exe), compressed folders (.zip, .rar), and files completely missing their extensions. Some of these are blocked at the server level, others are blocked at the spam filter, and the most suspicious are blocked before even hitting that, so if you can’t get your email delivered, consider what it actually is that you’re trying to send.


The spam filter is the first line of defense between the wild world of the internet and the peaceful garden of your inbox. Sort of. In actuality, it’s more complicated than that, but for simplicity’s sake, we’ll say that it is. The filter is an important and indispensable piece of the email puzzle, but it can also be the most frustrating when you just want to communicate with a client. The reason for this is simply due to the nature of the computer. A human can look at an email you’ve sent to Aunty Sue and tell pretty quickly whether it’s a nefarious phishing scam or a simple request to borrow Grand-dad’s vintage Rolex that he got for 50% off at the old pharmacy in Nigeria, but the spam filter isn’t human, and therefore it requires a more literal approach.

If you pasted my Rolex example into an email and sent it to someone, it would almost certainly get flagged somewhere down the line. That’s because a spam filter parses an email and assigns a score based on its contents. The most basic information it looks for is words that commonly occur in phishing emails; words like Rolex, pharmacy, and a slew of other words that are fun to giggle at but not likely appropriate to place within this article. Even a word as innocent as “pics” will net you 0.5 on the Canit spam index (a small amount, given that a typical spam threshold is a solid 5) and combos like “extra inches” (giggle) will cost you 3.1.

It goes beyond simply what words are used. Here are just some things that a spam filter will place against an email’s score:

  • Typing the subject line in all caps. In written text, this typically means you’re YELLING and want attention.
  • No subject line at all.
  • The message body is empty or includes nothing but a hyperlink.
  • The message body includes a tremendous number of pictures and very little or no text.
  • The Email includes foreign text (Cyrillic being the reddest of red flags).


There may be nothing I can do to get my package carrier to actually knock on my front door, but there’s lots of things that can be done to ensure your email makes it to its destination. Robots don’t care if it’s just little Jimmy trying to help his Grandmother get a deal on her heart medication, they can only see that the phrase “discount pharmaceuticals” is common parlance among phishermen. The rules vary between spam filters and email servers, but if you take a moment to consider what might look suspicious to the soulless sorting machines, trim your attachments, and avoid using words and phrases that might be associated with popular scams, you’ll improve that email’s chances of sliding into your intended recipient’s inbox. If you’re ever in doubt, just check with the help desk at Just Fix It. We’ll help you figure out why that email won’t fit in the email slot.

Just Fix It

230 Gage Avenue
Kitchener, Ontario
N2M 2C8, Canada

Hours of Operation

Just Fix It provides service 24 hours a day, 7 days a week - 365 days a year to our package clients.
Depo drop-off Monday - Friday 7am-7pm

Connect with us!

Phone & Fax

Phone: 1.519.880.8247
Toll Free: 1.886.349.8847
Fax: 1.519.880.8923

Traditional Helpdesk Support

Kitchener-Waterloo: 519.489.6770
Calgary: 403.770.3006
Canada and the US: 866.353.5717
Fax: 519.880.8923