The mailgw.py file attempts to catch the socket.sslerror, which is no longer present in 
python 3.3 and on:

https://docs.python.org/3/library/ssl.html#ssl.SSLError

As a result attempting to use mailgw.py will throw an exception:

AttributeError: module 'socket' has no attribute 'sslerror'. 

The attached simple patch fixes the issue for python3. However, this is going to end up 
skipping the error for python2.

NOTE: I had some communication around this issue in August of 2021 via email but sadly 
dropped the ball.

Hi Andrew,

I think I have a solution to the crash that preserves both python2 and
python3 handling of the sslerror. I have attached the patch. Do you have
an environment you can test in?

If not, do you think connecting via imaps to a non-ssl endpoint would cause the
error?

Actually I guess connecting to anything even a non-listening port should cause
the exception to be evaluated and throw a traceback right?

Thanks for bringing this to our attention and providing a patch.

-- rouilj

Hi Andrew:

Using nc I was able to cause an SSLError for testing.
With my patch plus adding back SSLError support for pops
both python 2 and 3, pops and imaps seem to handle the ssl
error fine.

changeset:   6582:3e8f2104753b

has the full patch and changelog.

Thanks for your report to trigger this work.

Have a great week.

-- rouilj

Great fix, thanks for the fast responses!

-Andrew